diff --git a/components/sessions/BUILD.gn b/components/sessions/BUILD.gn
index 6db298c09b968..6179da74819ea 100644
--- a/components/sessions/BUILD.gn
+++ b/components/sessions/BUILD.gn
@@ -136,7 +136,6 @@ source_set("shared") {
 
   public_deps = [
     ":session_id",
-    "//build:chromeos_buildflags",
     "//components/keyed_service/core",
     "//skia",
   ]
diff --git a/components/sessions/core/session_types.h b/components/sessions/core/session_types.h
index aa5bcf1948b47..1861d93a1a23d 100644
--- a/components/sessions/core/session_types.h
+++ b/components/sessions/core/session_types.h
@@ -14,7 +14,6 @@
 
 #include "base/time/time.h"
 #include "base/token.h"
-#include "build/chromeos_buildflags.h"
 #include "components/sessions/core/serialized_navigation_entry.h"
 #include "components/sessions/core/serialized_user_agent_override.h"
 #include "components/sessions/core/session_id.h"
@@ -156,7 +155,7 @@ struct SESSIONS_EXPORT SessionWindow {
     TYPE_APP = 2,
     TYPE_DEVTOOLS = 3,
     TYPE_APP_POPUP = 4,
-#if BUILDFLAG(IS_CHROMEOS_ASH)
+#if BUILDFLAG(IS_CHROMEOS)
     TYPE_CUSTOM_TAB = 5,
 #endif
   };
diff --git a/components/sessions/core/tab_restore_service_impl.cc b/components/sessions/core/tab_restore_service_impl.cc
index 2da47939180ec..a9e12ccf4cea8 100644
--- a/components/sessions/core/tab_restore_service_impl.cc
+++ b/components/sessions/core/tab_restore_service_impl.cc
@@ -253,7 +253,7 @@ bool DeserializeWindowType(int type_int,
     case sessions::SessionWindow::TYPE_APP:
     case sessions::SessionWindow::TYPE_DEVTOOLS:
     case sessions::SessionWindow::TYPE_APP_POPUP:
-#if BUILDFLAG(IS_CHROMEOS_ASH)
+#if BUILDFLAG(IS_CHROMEOS)
     case sessions::SessionWindow::TYPE_CUSTOM_TAB:
 #endif
       *type = static_cast<sessions::SessionWindow::WindowType>(type_int);
diff --git a/components/soda/BUILD.gn b/components/soda/BUILD.gn
index d6b0266c0c6d1..a77a42e784566 100644
--- a/components/soda/BUILD.gn
+++ b/components/soda/BUILD.gn
@@ -3,7 +3,6 @@
 # found in the LICENSE file.
 
 import("//build/buildflag_header.gni")
-import("//build/config/chromeos/ui_mode.gni")
 import("//components/soda/buildflags.gni")
 
 assert(!is_android)
@@ -26,13 +25,12 @@ component("soda") {
   deps = [
     ":constants",
     "//base",
-    "//build:chromeos_buildflags",
     "//components/live_caption:constants",
     "//components/prefs",
     "//media",
   ]
 
-  if (is_chromeos_ash) {
+  if (is_chromeos) {
     sources += [
       "soda_installer_impl_chromeos.cc",
       "soda_installer_impl_chromeos.h",
@@ -45,10 +43,6 @@ component("soda") {
       "//ui/base",
     ]
   }
-
-  if (is_chromeos_lacros) {
-    deps += [ "//chromeos/startup:startup" ]
-  }
 }
 
 source_set("constants") {
@@ -85,18 +79,14 @@ source_set("utils") {
     "//ui/base",
   ]
 
-  if (is_chromeos_ash) {
+  if (is_chromeos) {
     deps += [ "//ash/constants:constants" ]
   }
-
-  if (is_chromeos_lacros) {
-    deps += [ "//chromeos/startup:startup" ]
-  }
 }
 
 source_set("unit_tests") {
   testonly = true
-  if (is_chromeos_ash) {
+  if (is_chromeos) {
     sources = [ "soda_installer_impl_chromeos_unittest.cc" ]
 
     deps = [
diff --git a/components/soda/soda_features.cc b/components/soda/soda_features.cc
index 04c34dc0bb755..8f1b20b701b64 100644
--- a/components/soda/soda_features.cc
+++ b/components/soda/soda_features.cc
@@ -7,7 +7,7 @@
 #include "base/feature_list.h"
 
 namespace speech {
-#if BUILDFLAG(IS_CHROMEOS_ASH)
+#if BUILDFLAG(IS_CHROMEOS)
 BASE_FEATURE(kCrosExpandSodaLanguages,
              "CrosExpandSodaLanguages",
              base::FEATURE_ENABLED_BY_DEFAULT);
diff --git a/components/soda/soda_installer.cc b/components/soda/soda_installer.cc
index 4e13e669a3fec..474353f48466a 100644
--- a/components/soda/soda_installer.cc
+++ b/components/soda/soda_installer.cc
@@ -12,7 +12,6 @@
 #include "base/observer_list.h"
 #include "base/strings/string_split.h"
 #include "base/values.h"
-#include "build/chromeos_buildflags.h"
 #include "components/live_caption/pref_names.h"
 #include "components/prefs/pref_service.h"
 #include "components/prefs/scoped_user_pref_update.h"
@@ -20,10 +19,10 @@
 #include "components/soda/pref_names.h"
 #include "media/base/media_switches.h"
 
-#if BUILDFLAG(IS_CHROMEOS_ASH)
+#if BUILDFLAG(IS_CHROMEOS)
 #include "ash/constants/ash_features.h"
 #include "ash/constants/ash_pref_names.h"
-#endif  // BUILDFLAG(IS_CHROMEOS_ASH)
+#endif  // BUILDFLAG(IS_CHROMEOS)
 
 namespace {
 
@@ -41,10 +40,10 @@ SodaInstaller* g_instance = nullptr;
 
 // static
 SodaInstaller* SodaInstaller::GetInstance() {
-#if BUILDFLAG(IS_CHROMEOS_ASH)
+#if BUILDFLAG(IS_CHROMEOS)
   DCHECK(
       base::FeatureList::IsEnabled(ash::features::kOnDeviceSpeechRecognition));
-#endif  // BUILDFLAG(IS_CHROMEOS_ASH)
+#endif  // BUILDFLAG(IS_CHROMEOS)
   return g_instance;
 }
 
@@ -63,7 +62,7 @@ void SodaInstaller::RegisterLocalStatePrefs(PrefRegistrySimple* registry) {
   registry->RegisterTimePref(prefs::kSodaScheduledDeletionTime, base::Time());
   SodaInstaller::RegisterRegisteredLanguagePackPref(registry);
 
-#if !BUILDFLAG(IS_CHROMEOS_ASH)
+#if !BUILDFLAG(IS_CHROMEOS)
   // Handle non-Chrome-OS logic here. We need to keep the implementation of this
   // method in the parent class to avoid duplicate declaration build errors
   // (specifically on Windows).
@@ -74,16 +73,16 @@ void SodaInstaller::RegisterLocalStatePrefs(PrefRegistrySimple* registry) {
        kLanguageComponentConfigs) {
     registry->RegisterFilePathPref(config.config_path_pref, base::FilePath());
   }
-#endif  // !BUILDFLAG(IS_CHROMEOS_ASH)
+#endif  // !BUILDFLAG(IS_CHROMEOS)
 }
 
 void SodaInstaller::Init(PrefService* profile_prefs,
                          PrefService* global_prefs) {
-#if BUILDFLAG(IS_CHROMEOS_ASH)
+#if BUILDFLAG(IS_CHROMEOS)
   if (!base::FeatureList::IsEnabled(
           ash::features::kOnDeviceSpeechRecognition) ||
       soda_installer_initialized_) {
-#else  // !BUILDFLAG(IS_CHROMEOS_ASH)
+#else  // !BUILDFLAG(IS_CHROMEOS)
   if (soda_installer_initialized_) {
 #endif
     return;
@@ -301,13 +300,13 @@ std::optional<SodaInstaller::ErrorCode> SodaInstaller::GetSodaInstallErrorCode(
 }
 
 bool SodaInstaller::IsAnyFeatureUsingSodaEnabled(PrefService* prefs) {
-#if BUILDFLAG(IS_CHROMEOS_ASH)
+#if BUILDFLAG(IS_CHROMEOS)
   return prefs->GetBoolean(prefs::kLiveCaptionEnabled) ||
          prefs->GetBoolean(ash::prefs::kAccessibilityDictationEnabled) ||
          prefs->GetBoolean(ash::prefs::kProjectorCreationFlowEnabled) ||
          prefs->GetString(
              ash::prefs::kClassManagementToolsAvailabilitySetting) == "teacher";
-#else  // !BUILDFLAG(IS_CHROMEOS_ASH)
+#else  // !BUILDFLAG(IS_CHROMEOS)
   return prefs->GetBoolean(prefs::kLiveCaptionEnabled);
 #endif
 }
diff --git a/components/soda/soda_util.cc b/components/soda/soda_util.cc
index 9f198e483ddbb..3cf720a59c86e 100644
--- a/components/soda/soda_util.cc
+++ b/components/soda/soda_util.cc
@@ -8,21 +8,16 @@
 
 #include "base/feature_list.h"
 #include "build/build_config.h"
-#include "build/chromeos_buildflags.h"
 #include "components/soda/constants.h"
 #include "components/soda/soda_installer.h"
 #include "media/base/media_switches.h"
 #include "ui/base/l10n/l10n_util.h"
 
-#if BUILDFLAG(IS_CHROMEOS_ASH)
+#if BUILDFLAG(IS_CHROMEOS)
 #include "ash/constants/ash_features.h"
 #include "base/feature_list.h"
 #endif
 
-#if BUILDFLAG(IS_CHROMEOS_LACROS)
-#include "chromeos/startup/browser_params_proxy.h"
-#endif
-
 #if BUILDFLAG(IS_WIN)
 #include "base/win/windows_version.h"
 #endif
@@ -37,18 +32,9 @@ namespace {
 
 #if BUILDFLAG(IS_CHROMEOS)
 bool IsSupportedChromeOS() {
-// Some Chrome OS devices do not support on-device speech.
-#if BUILDFLAG(IS_CHROMEOS_ASH)
-  if (!base::FeatureList::IsEnabled(
-          ash::features::kOnDeviceSpeechRecognition)) {
-    return false;
-  }
-#elif BUILDFLAG(IS_CHROMEOS_LACROS)
-  if (!chromeos::BrowserParamsProxy::Get()->IsOndeviceSpeechSupported()) {
-    return false;
-  }
-#endif  // BUILDFLAG(IS_CHROMEOS_ASH)
-  return true;
+  // Some Chrome OS devices do not support on-device speech.
+  return base::FeatureList::IsEnabled(
+      ash::features::kOnDeviceSpeechRecognition);
 }
 #endif  // BUILDFLAG(IS_CHROMEOS)
 
diff --git a/components/storage_monitor/BUILD.gn b/components/storage_monitor/BUILD.gn
index c6bbb5ef6a8ac..3cce5f29463fb 100644
--- a/components/storage_monitor/BUILD.gn
+++ b/components/storage_monitor/BUILD.gn
@@ -2,7 +2,6 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-import("//build/config/chromeos/ui_mode.gni")
 import("//build/config/features.gni")
 
 static_library("storage_monitor") {
@@ -22,7 +21,6 @@ static_library("storage_monitor") {
 
   deps = [
     "//base",
-    "//build:chromeos_buildflags",
     "//content/public/browser",
     "//mojo/public/cpp/bindings",
     "//services/service_manager/public/cpp",
@@ -53,9 +51,7 @@ static_library("storage_monitor") {
       "ImageCaptureCore.framework",
       "UniformTypeIdentifiers.framework",
     ]
-  } else if (is_chromeos_ash) {
-    # For Chrome OS, |is_linux| is also true. Put this in an else-if block above
-    # the |is_linux| else-if block, so they do not clash.
+  } else if (is_chromeos) {
     sources += [
       "storage_monitor_chromeos.cc",
       "storage_monitor_chromeos.h",
@@ -74,7 +70,7 @@ static_library("storage_monitor") {
       ]
       deps += [ "//services/device/public/mojom" ]
     }
-  } else if (is_linux || is_chromeos_lacros) {
+  } else if (is_linux) {
     if (use_udev) {
       sources += [
         "mtab_watcher_linux.cc",
@@ -117,9 +113,9 @@ static_library("test_support") {
     "//content/public/browser",
   ]
 
-  deps = [ "//build:chromeos_buildflags" ]
+  deps = []
 
-  if (is_chromeos_ash) {
+  if (is_chromeos) {
     sources += [
       "test_media_transfer_protocol_manager_chromeos.cc",
       "test_media_transfer_protocol_manager_chromeos.h",
@@ -169,7 +165,8 @@ source_set("unit_tests") {
     frameworks = [ "UniformTypeIdentifiers.framework" ]
   }
 
-  if (is_chromeos_ash) {
+  if (is_chromeos) {
+    deps += [ "//chromeos/ash/components/disks:test_support" ]
     if (use_dbus) {
       deps += [
         "//services/device/public/mojom",
@@ -180,12 +177,9 @@ source_set("unit_tests") {
         "storage_monitor_chromeos_unittest.cc",
       ]
     }
-  } else if (is_linux || is_chromeos_lacros) {
+  } else if (is_linux) {
     if (use_udev) {
       sources += [ "storage_monitor_linux_unittest.cc" ]
     }
   }
-  if (is_chromeos_ash) {
-    deps += [ "//chromeos/ash/components/disks:test_support" ]
-  }
 }
diff --git a/components/storage_monitor/mtab_watcher_linux.h b/components/storage_monitor/mtab_watcher_linux.h
index 69687f61816bf..0f1fabe014c5f 100644
--- a/components/storage_monitor/mtab_watcher_linux.h
+++ b/components/storage_monitor/mtab_watcher_linux.h
@@ -5,12 +5,6 @@
 #ifndef COMPONENTS_STORAGE_MONITOR_MTAB_WATCHER_LINUX_H_
 #define COMPONENTS_STORAGE_MONITOR_MTAB_WATCHER_LINUX_H_
 
-#include "build/chromeos_buildflags.h"
-
-#if BUILDFLAG(IS_CHROMEOS_ASH)
-#error "ChromeOS does not use MtabWatcherLinux."
-#endif
-
 #include <map>
 
 #include "base/files/file_path.h"
@@ -19,6 +13,10 @@
 #include "base/sequence_checker.h"
 #include "build/build_config.h"
 
+#if BUILDFLAG(IS_CHROMEOS)
+#error "ChromeOS does not use MtabWatcherLinux."
+#endif
+
 namespace storage_monitor {
 
 // MtabWatcherLinux listens for mount point changes from a mtab file and
diff --git a/components/storage_monitor/storage_monitor.h b/components/storage_monitor/storage_monitor.h
index 6ec8a3521bc3f..71680e1cb1876 100644
--- a/components/storage_monitor/storage_monitor.h
+++ b/components/storage_monitor/storage_monitor.h
@@ -16,10 +16,9 @@
 #include "base/sequence_checker.h"
 #include "base/synchronization/lock.h"
 #include "build/build_config.h"
-#include "build/chromeos_buildflags.h"
 #include "components/storage_monitor/storage_info.h"
 
-#if BUILDFLAG(IS_CHROMEOS_ASH)
+#if BUILDFLAG(IS_CHROMEOS)
 #include "services/device/public/mojom/mtp_manager.mojom-forward.h"
 #endif
 
@@ -120,7 +119,7 @@ class StorageMonitor {
       std::wstring* storage_object_id) const = 0;
 #endif
 
-#if BUILDFLAG(IS_CHROMEOS_ASH)
+#if BUILDFLAG(IS_CHROMEOS)
   virtual device::mojom::MtpManager* media_transfer_protocol_manager() = 0;
 #endif
 
diff --git a/components/storage_monitor/storage_monitor_chromeos.h b/components/storage_monitor/storage_monitor_chromeos.h
index 431bacc53ae9a..68ede462e49c2 100644
--- a/components/storage_monitor/storage_monitor_chromeos.h
+++ b/components/storage_monitor/storage_monitor_chromeos.h
@@ -9,12 +9,6 @@
 #ifndef COMPONENTS_STORAGE_MONITOR_STORAGE_MONITOR_CHROMEOS_H_
 #define COMPONENTS_STORAGE_MONITOR_STORAGE_MONITOR_CHROMEOS_H_
 
-#include "build/chromeos_buildflags.h"
-
-#if !BUILDFLAG(IS_CHROMEOS_ASH)
-#error "Should only be used on ChromeOS."
-#endif
-
 #include <map>
 #include <memory>
 #include <string>
@@ -27,6 +21,10 @@
 #include "mojo/public/cpp/bindings/remote.h"
 #include "services/device/public/mojom/mtp_manager.mojom.h"
 
+#if !BUILDFLAG(IS_CHROMEOS)
+#error "Should only be used on ChromeOS."
+#endif
+
 namespace storage_monitor {
 
 class MtpManagerClientChromeOS;
diff --git a/components/storage_monitor/storage_monitor_linux.h b/components/storage_monitor/storage_monitor_linux.h
index aa6ac9b8af3c5..3657e2c2e61bd 100644
--- a/components/storage_monitor/storage_monitor_linux.h
+++ b/components/storage_monitor/storage_monitor_linux.h
@@ -10,12 +10,6 @@
 #ifndef COMPONENTS_STORAGE_MONITOR_STORAGE_MONITOR_LINUX_H_
 #define COMPONENTS_STORAGE_MONITOR_STORAGE_MONITOR_LINUX_H_
 
-#include "build/chromeos_buildflags.h"
-
-#if BUILDFLAG(IS_CHROMEOS_ASH)
-#error "Use the ChromeOS-specific implementation instead."
-#endif
-
 #include <map>
 #include <memory>
 #include <string>
@@ -29,6 +23,10 @@
 #include "components/storage_monitor/mtab_watcher_linux.h"
 #include "components/storage_monitor/storage_monitor.h"
 
+#if BUILDFLAG(IS_CHROMEOS)
+#error "Use the ChromeOS-specific implementation instead."
+#endif
+
 namespace base {
 class SequencedTaskRunner;
 }
diff --git a/components/storage_monitor/test_storage_monitor.cc b/components/storage_monitor/test_storage_monitor.cc
index e388b3688fe35..8a68e60c3b9ef 100644
--- a/components/storage_monitor/test_storage_monitor.cc
+++ b/components/storage_monitor/test_storage_monitor.cc
@@ -10,17 +10,16 @@
 #include "base/run_loop.h"
 #include "base/synchronization/waitable_event.h"
 #include "build/build_config.h"
-#include "build/chromeos_buildflags.h"
 #include "components/storage_monitor/storage_info.h"
 
-#if BUILDFLAG(IS_CHROMEOS_ASH)
+#if BUILDFLAG(IS_CHROMEOS)
 #include "components/storage_monitor/test_media_transfer_protocol_manager_chromeos.h"
 #endif
 
 namespace storage_monitor {
 
 TestStorageMonitor::TestStorageMonitor() : init_called_(false) {
-#if BUILDFLAG(IS_CHROMEOS_ASH)
+#if BUILDFLAG(IS_CHROMEOS)
   auto* fake_mtp_manager =
       TestMediaTransferProtocolManagerChromeOS::GetFakeMtpManager();
   fake_mtp_manager->AddReceiver(
@@ -115,7 +114,7 @@ bool TestStorageMonitor::GetMTPStorageInfoFromDeviceId(
 }
 #endif
 
-#if BUILDFLAG(IS_CHROMEOS_ASH)
+#if BUILDFLAG(IS_CHROMEOS)
 device::mojom::MtpManager*
 TestStorageMonitor::media_transfer_protocol_manager() {
   return media_transfer_protocol_manager_.get();
diff --git a/components/storage_monitor/test_storage_monitor.h b/components/storage_monitor/test_storage_monitor.h
index 0b4593dec0299..e12b5de22baf7 100644
--- a/components/storage_monitor/test_storage_monitor.h
+++ b/components/storage_monitor/test_storage_monitor.h
@@ -10,10 +10,9 @@
 #include <vector>
 
 #include "build/build_config.h"
-#include "build/chromeos_buildflags.h"
 #include "components/storage_monitor/storage_monitor.h"
 
-#if BUILDFLAG(IS_CHROMEOS_ASH)
+#if BUILDFLAG(IS_CHROMEOS)
 #include "mojo/public/cpp/bindings/remote.h"
 #include "services/device/public/mojom/mtp_manager.mojom.h"
 #endif
@@ -53,7 +52,7 @@ class TestStorageMonitor : public StorageMonitor {
       std::wstring* storage_object_id) const override;
 #endif
 
-#if BUILDFLAG(IS_CHROMEOS_ASH)
+#if BUILDFLAG(IS_CHROMEOS)
   device::mojom::MtpManager* media_transfer_protocol_manager() override;
 #endif
 
@@ -79,7 +78,7 @@ class TestStorageMonitor : public StorageMonitor {
   // Paths considered for testing purposes to be on removable storage.
   std::vector<base::FilePath> removable_paths_;
 
-#if BUILDFLAG(IS_CHROMEOS_ASH)
+#if BUILDFLAG(IS_CHROMEOS)
   mojo::Remote<device::mojom::MtpManager> media_transfer_protocol_manager_;
 #endif
 };
diff --git a/components/supervised_user/core/browser/child_account_service.cc b/components/supervised_user/core/browser/child_account_service.cc
index bf25357d438d3..1dc514175aab7 100644
--- a/components/supervised_user/core/browser/child_account_service.cc
+++ b/components/supervised_user/core/browser/child_account_service.cc
@@ -14,7 +14,6 @@
 #include "base/no_destructor.h"
 #include "base/values.h"
 #include "build/build_config.h"
-#include "build/chromeos_buildflags.h"
 #include "components/policy/core/common/policy_pref_names.h"
 #include "components/signin/public/base/consent_level.h"
 #include "components/signin/public/base/signin_switches.h"
diff --git a/components/supervised_user/core/browser/list_family_members_service_unittest.cc b/components/supervised_user/core/browser/list_family_members_service_unittest.cc
index f79ba9381919e..ad625a48aefb6 100644
--- a/components/supervised_user/core/browser/list_family_members_service_unittest.cc
+++ b/components/supervised_user/core/browser/list_family_members_service_unittest.cc
@@ -360,8 +360,6 @@ TEST_F(ListFamilyMembersServiceTest,
   test_list_family_members_service_->Shutdown();
 }
 
-// Sign-out test is not supported for ChromeOS
-#if !BUILDFLAG(IS_CHROMEOS_ASH)
 // Data cleanup is only available for Windows, Mac and Linux
 #if BUILDFLAG(IS_MAC) || BUILDFLAG(IS_LINUX) || BUILDFLAG(IS_WIN)
 TEST_F(ListFamilyMembersServiceTest, ListFamilyFetcherClearsResponseOnSignout) {
@@ -454,7 +452,6 @@ TEST_F(ListFamilyMembersServiceTest, ListFamilyFetcherResetsPrefOnSignout) {
   test_list_family_members_service_->Shutdown();
 }
 #endif  // BUILDFLAG(IS_MAC) || BUILDFLAG(IS_LINUX) || BUILDFLAG(IS_WIN)
-#endif  // !BUILDFLAG(IS_CHROMEOS_ASH)
 
 }  // namespace
 }  // namespace supervised_user
diff --git a/components/supervised_user/core/browser/supervised_user_url_filter.h b/components/supervised_user/core/browser/supervised_user_url_filter.h
index 4794f5694ed0a..6b5bd9f89550e 100644
--- a/components/supervised_user/core/browser/supervised_user_url_filter.h
+++ b/components/supervised_user/core/browser/supervised_user_url_filter.h
@@ -14,7 +14,6 @@
 #include "base/functional/callback_forward.h"
 #include "base/observer_list.h"
 #include "base/sequence_checker.h"
-#include "build/chromeos_buildflags.h"
 #include "components/safe_search_api/url_checker.h"
 #include "components/signin/public/identity_manager/identity_manager.h"
 #include "components/supervised_user/core/browser/supervised_user_error_page.h"
diff --git a/components/sync_preferences/BUILD.gn b/components/sync_preferences/BUILD.gn
index 6667fcf41cbdd..575b4e849b332 100644
--- a/components/sync_preferences/BUILD.gn
+++ b/components/sync_preferences/BUILD.gn
@@ -2,7 +2,6 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-import("//build/config/chromeos/ui_mode.gni")
 import("//build/config/features.gni")
 
 static_library("sync_preferences") {
@@ -27,7 +26,6 @@ static_library("sync_preferences") {
 
   deps = [
     "//base",
-    "//build:chromeos_buildflags",
     "//components/metrics/demographics",
     "//components/policy/core/browser",
     "//components/pref_registry",
@@ -35,7 +33,7 @@ static_library("sync_preferences") {
     "//components/sync",
   ]
 
-  if (is_chromeos_ash) {
+  if (is_chromeos) {
     deps += [ "//ash/constants" ]
   }
 }
@@ -104,7 +102,6 @@ source_set("unit_tests") {
     ":sync_preferences",
     ":test_support",
     "//base/test:test_support",
-    "//build:chromeos_buildflags",
     "//components/pref_registry",
     "//components/prefs",
     "//components/prefs:test_support",
@@ -113,7 +110,7 @@ source_set("unit_tests") {
     "//testing/gtest",
   ]
 
-  if (is_chromeos_ash) {
+  if (is_chromeos) {
     deps += [ "//ash/constants" ]
   }
 }
diff --git a/components/sync_preferences/common_syncable_prefs_database.cc b/components/sync_preferences/common_syncable_prefs_database.cc
index 5ecd85d9d9929..53d0e653bc575 100644
--- a/components/sync_preferences/common_syncable_prefs_database.cc
+++ b/components/sync_preferences/common_syncable_prefs_database.cc
@@ -274,7 +274,7 @@ constexpr auto kCommonSyncablePrefsAllowlist =
           PrefSensitivity::kNone, MergeBehavior::kNone}},
 // For Ash, the OS_PRIORITY_PREFERENCES equivalent is defined in
 // chrome/browser/sync/prefs/chrome_syncable_prefs_database.cc instead.
-#if !BUILDFLAG(IS_CHROMEOS_ASH)
+#if !BUILDFLAG(IS_CHROMEOS)
         {variations::kDogfoodGroupsSyncPrefName,
          {syncable_prefs_ids::kDogfoodGroupsSyncPrefName,
           syncer::PRIORITY_PREFERENCES, PrefSensitivity::kNone,
diff --git a/components/sync_preferences/dual_layer_user_pref_store.cc b/components/sync_preferences/dual_layer_user_pref_store.cc
index 3a4685b4b40e8..313cf0e53aa6d 100644
--- a/components/sync_preferences/dual_layer_user_pref_store.cc
+++ b/components/sync_preferences/dual_layer_user_pref_store.cc
@@ -15,7 +15,6 @@
 #include "base/observer_list.h"
 #include "base/strings/string_util.h"
 #include "base/values.h"
-#include "build/chromeos_buildflags.h"
 #include "components/sync/service/sync_service.h"
 #include "components/sync/service/sync_user_settings.h"
 #include "components/sync_preferences/pref_model_associator_client.h"
diff --git a/components/sync_preferences/dual_layer_user_pref_store_unittest.cc b/components/sync_preferences/dual_layer_user_pref_store_unittest.cc
index 6120a0f80ba6c..37adf0c19c747 100644
--- a/components/sync_preferences/dual_layer_user_pref_store_unittest.cc
+++ b/components/sync_preferences/dual_layer_user_pref_store_unittest.cc
@@ -12,7 +12,6 @@
 #include "base/test/mock_callback.h"
 #include "base/test/task_environment.h"
 #include "base/values.h"
-#include "build/chromeos_buildflags.h"
 #include "components/prefs/testing_pref_store.h"
 #include "components/sync/test/test_sync_service.h"
 #include "components/sync_preferences/pref_model_associator_client.h"
@@ -189,7 +188,7 @@ class DualLayerUserPrefStoreTest : public DualLayerUserPrefStoreTestBase {
     // data types appropriately.
     dual_layer_store_->EnableType(syncer::PREFERENCES);
     dual_layer_store_->EnableType(syncer::PRIORITY_PREFERENCES);
-#if BUILDFLAG(IS_CHROMEOS_ASH)
+#if BUILDFLAG(IS_CHROMEOS)
     dual_layer_store_->EnableType(syncer::OS_PREFERENCES);
     dual_layer_store_->EnableType(syncer::OS_PRIORITY_PREFERENCES);
 #endif
@@ -1257,7 +1256,7 @@ class DualLayerUserPrefStoreMergeTest : public testing::Test {
 
     dual_layer_store_->EnableType(syncer::PREFERENCES);
     dual_layer_store_->EnableType(syncer::PRIORITY_PREFERENCES);
-#if BUILDFLAG(IS_CHROMEOS_ASH)
+#if BUILDFLAG(IS_CHROMEOS)
     dual_layer_store_->EnableType(syncer::OS_PREFERENCES);
     dual_layer_store_->EnableType(syncer::OS_PRIORITY_PREFERENCES);
 #endif
diff --git a/components/sync_preferences/pref_model_associator.cc b/components/sync_preferences/pref_model_associator.cc
index 68820d7ca623d..790889b1d9a4e 100644
--- a/components/sync_preferences/pref_model_associator.cc
+++ b/components/sync_preferences/pref_model_associator.cc
@@ -22,7 +22,6 @@
 #include "base/observer_list.h"
 #include "base/types/expected_macros.h"
 #include "base/values.h"
-#include "build/chromeos_buildflags.h"
 #include "components/sync/base/data_type.h"
 #include "components/sync/base/features.h"
 #include "components/sync/model/sync_change.h"
@@ -43,7 +42,7 @@ const sync_pb::PreferenceSpecifics& GetSpecifics(const syncer::SyncData& pref) {
       return pref.GetSpecifics().preference();
     case syncer::PRIORITY_PREFERENCES:
       return pref.GetSpecifics().priority_preference().preference();
-#if BUILDFLAG(IS_CHROMEOS_ASH)
+#if BUILDFLAG(IS_CHROMEOS)
     case syncer::OS_PREFERENCES:
       return pref.GetSpecifics().os_preference().preference();
     case syncer::OS_PRIORITY_PREFERENCES:
@@ -77,7 +76,7 @@ PrefModelAssociator::PrefModelAssociator(
       user_prefs_(user_prefs),
       dual_layer_user_prefs_(nullptr) {
   DCHECK_CALLED_ON_VALID_SEQUENCE(sequence_checker_);
-#if BUILDFLAG(IS_CHROMEOS_ASH)
+#if BUILDFLAG(IS_CHROMEOS)
   DCHECK(type_ == syncer::PREFERENCES ||
          type_ == syncer::PRIORITY_PREFERENCES ||
          type_ == syncer::OS_PREFERENCES ||
@@ -119,7 +118,7 @@ sync_pb::PreferenceSpecifics* PrefModelAssociator::GetMutableSpecifics(
       return specifics->mutable_preference();
     case syncer::PRIORITY_PREFERENCES:
       return specifics->mutable_priority_preference()->mutable_preference();
-#if BUILDFLAG(IS_CHROMEOS_ASH)
+#if BUILDFLAG(IS_CHROMEOS)
     case syncer::OS_PREFERENCES:
       return specifics->mutable_os_preference()->mutable_preference();
     case syncer::OS_PRIORITY_PREFERENCES:
diff --git a/components/sync_preferences/pref_model_associator_unittest.cc b/components/sync_preferences/pref_model_associator_unittest.cc
index e7e3fc977f1b3..42594826555cc 100644
--- a/components/sync_preferences/pref_model_associator_unittest.cc
+++ b/components/sync_preferences/pref_model_associator_unittest.cc
@@ -44,10 +44,10 @@ const char kDictionaryPrefName[] = "pref.dictionary";
 const char kCustomMergePrefName[] = "pref.custom";
 
 const char kStringPriorityPrefName[] = "priority.pref.string";
-#if BUILDFLAG(IS_CHROMEOS_ASH)
+#if BUILDFLAG(IS_CHROMEOS)
 const char kStringOsPrefName[] = "os.pref.string";
 const char kStringOsPriorityPrefName[] = "os.priority.pref.string";
-#endif  // BUILDFLAG(IS_CHROMEOS_ASH)
+#endif  // BUILDFLAG(IS_CHROMEOS)
 
 // Assigning an id of 0 to all the test prefs.
 const TestSyncablePrefsDatabase::PrefsMap kSyncablePrefsDatabase = {
@@ -64,13 +64,13 @@ const TestSyncablePrefsDatabase::PrefsMap kSyncablePrefsDatabase = {
     {kStringPriorityPrefName,
      {0, syncer::PRIORITY_PREFERENCES, PrefSensitivity::kNone,
       MergeBehavior::kNone}},
-#if BUILDFLAG(IS_CHROMEOS_ASH)
+#if BUILDFLAG(IS_CHROMEOS)
     {kStringOsPrefName,
      {0, syncer::OS_PREFERENCES, PrefSensitivity::kNone, MergeBehavior::kNone}},
     {kStringOsPriorityPrefName,
      {0, syncer::OS_PRIORITY_PREFERENCES, PrefSensitivity::kNone,
       MergeBehavior::kNone}},
-#endif  // BUILDFLAG(IS_CHROMEOS_ASH)
+#endif  // BUILDFLAG(IS_CHROMEOS)
 };
 
 // Creates SyncData for a remote pref change.
@@ -597,7 +597,7 @@ TEST_F(SyncablePrefsDatabaseTest, ShouldAllowRegisteringSyncablePriorityPrefs) {
               NotNull());
 }
 
-#if BUILDFLAG(IS_CHROMEOS_ASH)
+#if BUILDFLAG(IS_CHROMEOS)
 TEST_F(SyncablePrefsDatabaseTest, ShouldAllowRegisteringSyncableOSPrefs) {
   pref_registry_->RegisterStringPref(
       kStringOsPrefName, std::string(),
@@ -660,7 +660,7 @@ TEST_F(SyncablePrefsDatabaseDeathTest,
       kExpectedErrorMessageHint);
 }
 
-#if BUILDFLAG(IS_CHROMEOS_ASH)
+#if BUILDFLAG(IS_CHROMEOS)
 TEST_F(SyncablePrefsDatabaseDeathTest, ShouldFailRegisteringIllegalOSPrefs) {
   const std::string kIllegalStringPrefName = "not-allowed_string_pref";
   const std::string kIllegalListPrefName = "not-allowed_list_pref";
@@ -721,7 +721,7 @@ TEST_F(SyncablePrefsDatabaseDeathTest,
                                kStringPriorityPrefName, std::string(),
                                user_prefs::PrefRegistrySyncable::SYNCABLE_PREF),
                            kExpectedErrorMessageHint);
-#if BUILDFLAG(IS_CHROMEOS_ASH)
+#if BUILDFLAG(IS_CHROMEOS)
   EXPECT_DCHECK_DEATH_WITH(
       pref_registry_->RegisterStringPref(
           kStringOsPrefName, std::string(),
diff --git a/components/sync_preferences/pref_service_syncable.cc b/components/sync_preferences/pref_service_syncable.cc
index 329a77a218765..4430d97e5cf16 100644
--- a/components/sync_preferences/pref_service_syncable.cc
+++ b/components/sync_preferences/pref_service_syncable.cc
@@ -12,7 +12,6 @@
 #include "base/functional/callback_helpers.h"
 #include "base/observer_list.h"
 #include "base/scoped_observation.h"
-#include "build/chromeos_buildflags.h"
 #include "components/metrics/demographics/user_demographics.h"
 #include "components/pref_registry/pref_registry_syncable.h"
 #include "components/prefs/in_memory_pref_store.h"
@@ -27,7 +26,7 @@
 #include "components/sync_preferences/pref_service_syncable_observer.h"
 #include "components/sync_preferences/synced_pref_observer.h"
 
-#if BUILDFLAG(IS_CHROMEOS_ASH)
+#if BUILDFLAG(IS_CHROMEOS)
 #include "ash/constants/ash_features.h"
 #endif
 
@@ -92,7 +91,7 @@ PrefServiceSyncable::PrefServiceSyncable(
       priority_pref_sync_associator_(pref_model_associator_client,
                                      user_prefs,
                                      syncer::PRIORITY_PREFERENCES),
-#if BUILDFLAG(IS_CHROMEOS_ASH)
+#if BUILDFLAG(IS_CHROMEOS)
       os_pref_sync_associator_(pref_model_associator_client,
                                user_prefs,
                                syncer::OS_PREFERENCES),
@@ -127,7 +126,7 @@ PrefServiceSyncable::PrefServiceSyncable(
       priority_pref_sync_associator_(pref_model_associator_client,
                                      dual_layer_user_prefs,
                                      syncer::PRIORITY_PREFERENCES),
-#if BUILDFLAG(IS_CHROMEOS_ASH)
+#if BUILDFLAG(IS_CHROMEOS)
       os_pref_sync_associator_(pref_model_associator_client,
                                dual_layer_user_prefs,
                                syncer::OS_PREFERENCES),
@@ -145,7 +144,7 @@ PrefServiceSyncable::PrefServiceSyncable(
 void PrefServiceSyncable::ConnectAssociatorsAndRegisterPreferences() {
   pref_sync_associator_.SetPrefService(this);
   priority_pref_sync_associator_.SetPrefService(this);
-#if BUILDFLAG(IS_CHROMEOS_ASH)
+#if BUILDFLAG(IS_CHROMEOS)
   os_pref_sync_associator_.SetPrefService(this);
   os_priority_pref_sync_associator_.SetPrefService(this);
 #endif
@@ -213,7 +212,7 @@ bool PrefServiceSyncable::IsPrioritySyncing() {
   return priority_pref_sync_associator_.models_associated();
 }
 
-#if BUILDFLAG(IS_CHROMEOS_ASH)
+#if BUILDFLAG(IS_CHROMEOS)
 bool PrefServiceSyncable::AreOsPrefsSyncing() {
   return os_pref_sync_associator_.models_associated();
 }
@@ -221,7 +220,7 @@ bool PrefServiceSyncable::AreOsPrefsSyncing() {
 bool PrefServiceSyncable::AreOsPriorityPrefsSyncing() {
   return os_priority_pref_sync_associator_.models_associated();
 }
-#endif  // BUILDFLAG(IS_CHROMEOS_ASH)
+#endif  // BUILDFLAG(IS_CHROMEOS)
 
 void PrefServiceSyncable::AddObserver(PrefServiceSyncableObserver* observer) {
   observer_list_.AddObserver(observer);
@@ -239,7 +238,7 @@ syncer::SyncableService* PrefServiceSyncable::GetSyncableService(
       return &pref_sync_associator_;
     case syncer::PRIORITY_PREFERENCES:
       return &priority_pref_sync_associator_;
-#if BUILDFLAG(IS_CHROMEOS_ASH)
+#if BUILDFLAG(IS_CHROMEOS)
     case syncer::OS_PREFERENCES:
       return &os_pref_sync_associator_;
     case syncer::OS_PRIORITY_PREFERENCES:
@@ -262,7 +261,7 @@ void PrefServiceSyncable::AddSyncedPrefObserver(const std::string& name,
                                                 SyncedPrefObserver* observer) {
   pref_sync_associator_.AddSyncedPrefObserver(name, observer);
   priority_pref_sync_associator_.AddSyncedPrefObserver(name, observer);
-#if BUILDFLAG(IS_CHROMEOS_ASH)
+#if BUILDFLAG(IS_CHROMEOS)
   os_pref_sync_associator_.AddSyncedPrefObserver(name, observer);
   os_priority_pref_sync_associator_.AddSyncedPrefObserver(name, observer);
 #endif
@@ -273,7 +272,7 @@ void PrefServiceSyncable::RemoveSyncedPrefObserver(
     SyncedPrefObserver* observer) {
   pref_sync_associator_.RemoveSyncedPrefObserver(name, observer);
   priority_pref_sync_associator_.RemoveSyncedPrefObserver(name, observer);
-#if BUILDFLAG(IS_CHROMEOS_ASH)
+#if BUILDFLAG(IS_CHROMEOS)
   os_pref_sync_associator_.RemoveSyncedPrefObserver(name, observer);
   os_priority_pref_sync_associator_.RemoveSyncedPrefObserver(name, observer);
 #endif
@@ -290,7 +289,7 @@ void PrefServiceSyncable::AddRegisteredSyncablePreference(std::string_view path,
     priority_pref_sync_associator_.RegisterPref(path);
     return;
   }
-#if BUILDFLAG(IS_CHROMEOS_ASH)
+#if BUILDFLAG(IS_CHROMEOS)
   if (flags & user_prefs::PrefRegistrySyncable::SYNCABLE_OS_PREF) {
     os_pref_sync_associator_.RegisterPref(path);
     return;
diff --git a/components/sync_preferences/pref_service_syncable.h b/components/sync_preferences/pref_service_syncable.h
index c0c9f01b24afe..c670c1cb91ce2 100644
--- a/components/sync_preferences/pref_service_syncable.h
+++ b/components/sync_preferences/pref_service_syncable.h
@@ -15,7 +15,6 @@
 #include "base/functional/callback_forward.h"
 #include "base/functional/callback_helpers.h"
 #include "base/observer_list.h"
-#include "build/chromeos_buildflags.h"
 #include "components/pref_registry/pref_registry_syncable.h"
 #include "components/prefs/pref_service.h"
 #include "components/sync_preferences/pref_model_associator.h"
@@ -95,7 +94,7 @@ class PrefServiceSyncable : public PrefService,
   // priority preferences.
   bool IsPrioritySyncing();
 
-#if BUILDFLAG(IS_CHROMEOS_ASH)
+#if BUILDFLAG(IS_CHROMEOS)
   // As above, but for OS preferences.
   bool AreOsPrefsSyncing();
 
@@ -138,7 +137,7 @@ class PrefServiceSyncable : public PrefService,
   PrefModelAssociator pref_sync_associator_;
   PrefModelAssociator priority_pref_sync_associator_;
 
-#if BUILDFLAG(IS_CHROMEOS_ASH)
+#if BUILDFLAG(IS_CHROMEOS)
   // Associators for Chrome OS system preferences.
   PrefModelAssociator os_pref_sync_associator_;
   PrefModelAssociator os_priority_pref_sync_associator_;
diff --git a/components/sync_preferences/pref_service_syncable_unittest.cc b/components/sync_preferences/pref_service_syncable_unittest.cc
index 00bbb3b727d9c..7e4262db1579c 100644
--- a/components/sync_preferences/pref_service_syncable_unittest.cc
+++ b/components/sync_preferences/pref_service_syncable_unittest.cc
@@ -16,7 +16,6 @@
 #include "base/test/metrics/histogram_tester.h"
 #include "base/test/scoped_feature_list.h"
 #include "base/values.h"
-#include "build/chromeos_buildflags.h"
 #include "components/pref_registry/pref_registry_syncable.h"
 #include "components/prefs/pref_notifier_impl.h"
 #include "components/prefs/scoped_user_pref_update.h"
@@ -41,7 +40,7 @@
 #include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
-#if BUILDFLAG(IS_CHROMEOS_ASH)
+#if BUILDFLAG(IS_CHROMEOS)
 #include "testing/gmock/include/gmock/gmock-matchers.h"
 #endif
 
@@ -74,7 +73,7 @@ const char kNonDefaultCharsetValue[] = "foo";
 const char kDefaultCharsetValue[] = "utf-8";
 const char kBrowserPrefName[] = "browser_pref";
 const char kBrowserPriorityPrefName[] = "browser_priority_pref";
-#if BUILDFLAG(IS_CHROMEOS_ASH)
+#if BUILDFLAG(IS_CHROMEOS)
 const char kOsPrefName[] = "os_pref";
 const char kOsPriorityPrefName[] = "os_priority_pref";
 #endif
@@ -101,7 +100,7 @@ const TestSyncablePrefsDatabase::PrefsMap kSyncablePrefsDatabase = {
     {kBrowserPriorityPrefName,
      {8, syncer::PRIORITY_PREFERENCES, PrefSensitivity::kNone,
       MergeBehavior::kNone}},
-#if BUILDFLAG(IS_CHROMEOS_ASH)
+#if BUILDFLAG(IS_CHROMEOS)
     {kOsPrefName,
      {9, syncer::OS_PREFERENCES, PrefSensitivity::kNone, MergeBehavior::kNone}},
     {kOsPriorityPrefName,
@@ -129,7 +128,7 @@ std::optional<base::Value> FindValue(
   return std::nullopt;
 }
 
-#if BUILDFLAG(IS_CHROMEOS_ASH)
+#if BUILDFLAG(IS_CHROMEOS)
 constexpr DataTypeSet kAllPreferenceDataTypes = {
     syncer::PREFERENCES, syncer::PRIORITY_PREFERENCES, syncer::OS_PREFERENCES,
     syncer::OS_PRIORITY_PREFERENCES};
@@ -138,7 +137,7 @@ MATCHER_P(MatchesDataType, data_type, "") {
   const syncer::SyncChange& sync_change = arg;
   return Matches(data_type)(sync_change.sync_data().GetDataType());
 }
-#endif  // BUILDFLAG(IS_CHROMEOS_ASH)
+#endif  // BUILDFLAG(IS_CHROMEOS)
 
 class TestSyncProcessorStub : public syncer::SyncChangeProcessor {
  public:
@@ -991,7 +990,7 @@ TEST_F(PrefServiceSyncableTest, DeletePreference) {
   EXPECT_TRUE(pref->IsDefaultValue());
 }
 
-#if BUILDFLAG(IS_CHROMEOS_ASH)
+#if BUILDFLAG(IS_CHROMEOS)
 // The Chrome OS tests exercise pref model association that happens in the
 // constructor of PrefServiceSyncable. The tests must register prefs first,
 // then create the PrefServiceSyncable object. The tests live in this file
@@ -1391,7 +1390,7 @@ TEST_F(PrefServiceSyncableChromeOsTest,
   }
 }
 
-#endif  // BUILDFLAG(IS_CHROMEOS_ASH)
+#endif  // BUILDFLAG(IS_CHROMEOS)
 
 class PrefServiceSyncableFactoryTest : public PrefServiceSyncableTest {
  public:
@@ -1421,7 +1420,7 @@ TEST_F(PrefServiceSyncableFactoryTest,
       static_cast<PrefModelAssociator*>(
           pref_service->GetSyncableService(syncer::PRIORITY_PREFERENCES))
           ->IsUsingDualLayerUserPrefStoreForTesting());
-#if BUILDFLAG(IS_CHROMEOS_ASH)
+#if BUILDFLAG(IS_CHROMEOS)
   EXPECT_FALSE(static_cast<PrefModelAssociator*>(
                    pref_service->GetSyncableService(syncer::OS_PREFERENCES))
                    ->IsUsingDualLayerUserPrefStoreForTesting());
@@ -1445,7 +1444,7 @@ TEST_F(PrefServiceSyncableFactoryTest,
       static_cast<PrefModelAssociator*>(
           pref_service->GetSyncableService(syncer::PRIORITY_PREFERENCES))
           ->IsUsingDualLayerUserPrefStoreForTesting());
-#if BUILDFLAG(IS_CHROMEOS_ASH)
+#if BUILDFLAG(IS_CHROMEOS)
   EXPECT_TRUE(static_cast<PrefModelAssociator*>(
                   pref_service->GetSyncableService(syncer::OS_PREFERENCES))
                   ->IsUsingDualLayerUserPrefStoreForTesting());
diff --git a/components/sync_preferences/syncable_prefs_database.cc b/components/sync_preferences/syncable_prefs_database.cc
index aa71d316f16e7..9c97b08e0ad44 100644
--- a/components/sync_preferences/syncable_prefs_database.cc
+++ b/components/sync_preferences/syncable_prefs_database.cc
@@ -7,7 +7,6 @@
 #include <string_view>
 
 #include "base/logging.h"
-#include "build/chromeos_buildflags.h"
 
 namespace sync_preferences {
 
diff --git a/components/sync_preferences/syncable_prefs_database.h b/components/sync_preferences/syncable_prefs_database.h
index f127c7ac5661f..f8dfbbac8a9f3 100644
--- a/components/sync_preferences/syncable_prefs_database.h
+++ b/components/sync_preferences/syncable_prefs_database.h
@@ -11,7 +11,6 @@
 
 #include "base/check.h"
 #include "build/build_config.h"
-#include "build/chromeos_buildflags.h"
 #include "components/sync/base/data_type.h"
 
 namespace sync_preferences {
@@ -56,10 +55,10 @@ class SyncablePrefMetadata {
         merge_behaviour_(merge_behavior) {
     CHECK(data_type_ == syncer::PREFERENCES ||
           data_type_ == syncer::PRIORITY_PREFERENCES
-#if BUILDFLAG(IS_CHROMEOS_ASH)
+#if BUILDFLAG(IS_CHROMEOS)
           || data_type_ == syncer::OS_PREFERENCES ||
           data_type_ == syncer::OS_PRIORITY_PREFERENCES
-#endif  // BUILDFLAG(IS_CHROMEOS_ASH)
+#endif  // BUILDFLAG(IS_CHROMEOS)
           )
         << "Invalid type " << data_type_
         << " for syncable pref with id=" << syncable_pref_id_;
diff --git a/components/system_media_controls/linux/buildflags/buildflags.gni b/components/system_media_controls/linux/buildflags/buildflags.gni
index 693bed3a79a22..539eea3c1fff6 100644
--- a/components/system_media_controls/linux/buildflags/buildflags.gni
+++ b/components/system_media_controls/linux/buildflags/buildflags.gni
@@ -2,11 +2,10 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-import("//build/config/chromeos/ui_mode.gni")
 import("//build/config/features.gni")
 
 declare_args() {
   # Enables Chromium implementation of the MPRIS D-Bus interface for controlling
   # media playback. See ../README.md for details.
-  use_mpris = (is_linux || is_chromeos_lacros) && use_dbus
+  use_mpris = is_linux && use_dbus
 }
diff --git a/components/translate/core/browser/BUILD.gn b/components/translate/core/browser/BUILD.gn
index 5510f45387e91..1063102bd5fa8 100644
--- a/components/translate/core/browser/BUILD.gn
+++ b/components/translate/core/browser/BUILD.gn
@@ -51,7 +51,6 @@ static_library("browser") {
   deps = [
     "//base",
     "//base:i18n",
-    "//build:chromeos_buildflags",
     "//components/assist_ranker",
     "//components/assist_ranker/proto",
     "//components/keyed_service/core",
@@ -111,7 +110,6 @@ source_set("unit_tests") {
     ":browser",
     ":test_support",
     "//base",
-    "//build:chromeos_buildflags",
     "//components/assist_ranker",
     "//components/assist_ranker/proto",
     "//components/infobars/core",
@@ -154,7 +152,6 @@ source_set("test_support") {
   ]
   deps = [
     "//base",
-    "//build:chromeos_buildflags",
     "//components/infobars/core",
     "//components/language/core/browser",
     "//components/sync_preferences",
diff --git a/components/translate/core/browser/mock_translate_client.cc b/components/translate/core/browser/mock_translate_client.cc
index db697642cdade..ff046fb1da98d 100644
--- a/components/translate/core/browser/mock_translate_client.cc
+++ b/components/translate/core/browser/mock_translate_client.cc
@@ -4,7 +4,6 @@
 
 #include <memory>
 
-#include "build/chromeos_buildflags.h"
 #include "components/translate/core/browser/mock_translate_client.h"
 #include "components/translate/core/browser/translate_prefs.h"
 
@@ -12,7 +11,7 @@ namespace translate {
 
 namespace testing {
 
-#if BUILDFLAG(IS_CHROMEOS_ASH)
+#if BUILDFLAG(IS_CHROMEOS)
 const char* preferred_languages_prefs = "settings.language.preferred_languages";
 #else
 const char* preferred_languages_prefs = nullptr;
diff --git a/components/translate/core/browser/translate_infobar_delegate_unittest.cc b/components/translate/core/browser/translate_infobar_delegate_unittest.cc
index ea310f40c261e..4071b76f4c03c 100644
--- a/components/translate/core/browser/translate_infobar_delegate_unittest.cc
+++ b/components/translate/core/browser/translate_infobar_delegate_unittest.cc
@@ -8,7 +8,6 @@
 #include <vector>
 
 #include "base/test/task_environment.h"
-#include "build/chromeos_buildflags.h"
 #include "components/infobars/core/infobar.h"
 #include "components/infobars/core/infobar_manager.h"
 #include "components/language/core/browser/accept_languages_service.h"
@@ -105,7 +104,7 @@ class TranslateInfoBarDelegateTest : public ::testing::Test {
     language::LanguagePrefs::RegisterProfilePrefs(pref_service_->registry());
     pref_service_->SetString(testing::accept_languages_prefs, std::string());
     pref_service_->SetString(language::prefs::kAcceptLanguages, std::string());
-#if BUILDFLAG(IS_CHROMEOS_ASH)
+#if BUILDFLAG(IS_CHROMEOS)
     pref_service_->SetString(language::prefs::kPreferredLanguages,
                              std::string());
 #endif
@@ -290,7 +289,7 @@ TEST_F(TranslateInfoBarDelegateTest, IsTranslatableLanguage) {
   base::Value::List& update_list = update.Get();
   update_list.Append(kSourceLanguage);
   pref_service_->SetString(language::prefs::kAcceptLanguages, kSourceLanguage);
-#if BUILDFLAG(IS_CHROMEOS_ASH)
+#if BUILDFLAG(IS_CHROMEOS)
   pref_service_->SetString(language::prefs::kPreferredLanguages,
                            kSourceLanguage);
 #endif
diff --git a/components/translate/core/browser/translate_manager_unittest.cc b/components/translate/core/browser/translate_manager_unittest.cc
index bf0c1d106136a..9b428f1a3c311 100644
--- a/components/translate/core/browser/translate_manager_unittest.cc
+++ b/components/translate/core/browser/translate_manager_unittest.cc
@@ -15,7 +15,6 @@
 #include "base/test/scoped_feature_list.h"
 #include "base/test/task_environment.h"
 #include "build/build_config.h"
-#include "build/chromeos_buildflags.h"
 #include "components/infobars/core/infobar.h"
 #include "components/language/core/browser/accept_languages_service.h"
 #include "components/language/core/browser/language_model.h"
@@ -125,7 +124,7 @@ struct ProfilePrefRegistration {
       sync_preferences::TestingPrefServiceSyncable* prefs) {
     language::LanguagePrefs::RegisterProfilePrefs(prefs->registry());
     prefs->SetString(accept_languages_prefs, std::string());
-#if BUILDFLAG(IS_CHROMEOS_ASH)
+#if BUILDFLAG(IS_CHROMEOS)
     prefs->SetString(preferred_languages_prefs, std::string());
 #endif
     TranslatePrefs::RegisterProfilePrefs(prefs->registry());
diff --git a/components/translate/core/browser/translate_prefs.cc b/components/translate/core/browser/translate_prefs.cc
index 7e556a9a85653..ca7cab8efac92 100644
--- a/components/translate/core/browser/translate_prefs.cc
+++ b/components/translate/core/browser/translate_prefs.cc
@@ -22,7 +22,6 @@
 #include "base/strings/utf_string_conversions.h"
 #include "base/values.h"
 #include "build/build_config.h"
-#include "build/chromeos_buildflags.h"
 #include "components/language/core/browser/accept_languages_service.h"
 #include "components/language/core/browser/language_prefs.h"
 #include "components/language/core/browser/pref_names.h"
@@ -213,7 +212,7 @@ void TranslatePrefs::ResetToDefaults() {
 // static
 base::Value::List TranslatePrefs::GetDefaultBlockedLanguages() {
   base::Value::List languages;
-#if BUILDFLAG(IS_CHROMEOS_ASH)
+#if BUILDFLAG(IS_CHROMEOS)
   // Preferred languages.
   std::string language = language::kFallbackInputMethodLocale;
   language::ToTranslateLanguageSynonym(&language);
diff --git a/components/translate/core/browser/translate_prefs_unittest.cc b/components/translate/core/browser/translate_prefs_unittest.cc
index 3543d69a6de37..6ea1aa2657446 100644
--- a/components/translate/core/browser/translate_prefs_unittest.cc
+++ b/components/translate/core/browser/translate_prefs_unittest.cc
@@ -19,7 +19,6 @@
 #include "base/time/time.h"
 #include "base/values.h"
 #include "build/build_config.h"
-#include "build/chromeos_buildflags.h"
 #include "components/language/core/browser/language_prefs.h"
 #include "components/language/core/browser/language_prefs_test_util.h"
 #include "components/language/core/browser/pref_names.h"
@@ -71,7 +70,7 @@ class TranslatePrefsTest : public testing::Test {
 
   void SetUp() override {
     prefs_.SetString(language::prefs::kAcceptLanguages, std::string());
-#if BUILDFLAG(IS_CHROMEOS_ASH)
+#if BUILDFLAG(IS_CHROMEOS)
     prefs_.SetString(language::prefs::kPreferredLanguages, std::string());
 #endif
     prefs_.registry()->RegisterBooleanPref(
@@ -591,7 +590,7 @@ TEST_F(TranslatePrefsTest, MoveLanguageUp) {
                                       {"it", "es"});
   accept_languages_tester_->ExpectAcceptLanguagePrefs("it,en,fr,es");
 
-#if !BUILDFLAG(IS_CHROMEOS_ASH)
+#if !BUILDFLAG(IS_CHROMEOS)
   //---------------------------------------------------------------------------
   // Move with policy-forced languages present.
   // Forced languages should always remain at the top of the languages list and
@@ -720,7 +719,7 @@ TEST_F(TranslatePrefsTest, MoveLanguageUp) {
                                       {"en", "fr", "it", "es", "zh"});
   accept_languages_tester_->ExpectAcceptLanguagePrefs("es,en,fr,it,zh");
 
-#if !BUILDFLAG(IS_CHROMEOS_ASH)
+#if !BUILDFLAG(IS_CHROMEOS)
   //---------------------------------------------------------------------------
   // Move with policy-forced languages present.
   // Only test on non-Chrome OS platforms.
@@ -810,7 +809,7 @@ TEST_F(TranslatePrefsTest, MoveLanguageDown) {
                                       {"fr", "it"});
   accept_languages_tester_->ExpectAcceptLanguagePrefs("en,fr,es,it");
 
-#if !BUILDFLAG(IS_CHROMEOS_ASH)
+#if !BUILDFLAG(IS_CHROMEOS)
   //---------------------------------------------------------------------------
   // Move with policy-forced languages present.
   // Only test on non-Chrome OS platforms.
diff --git a/components/translate/core/browser/translate_ui_delegate.cc b/components/translate/core/browser/translate_ui_delegate.cc
index bb402a9360de5..0e711231d3500 100644
--- a/components/translate/core/browser/translate_ui_delegate.cc
+++ b/components/translate/core/browser/translate_ui_delegate.cc
@@ -51,7 +51,7 @@ TranslateUIDelegate::TranslateUIDelegate(
             language::kContentLanguagesInLanguagePicker,
             language::kContentLanguagesDisableObserversParam,
             false /* default */)) {
-#if BUILDFLAG(IS_CHROMEOS_ASH)
+#if BUILDFLAG(IS_CHROMEOS)
       const std::string& pref_name = language::prefs::kPreferredLanguages;
 #else
       const std::string& pref_name = language::prefs::kAcceptLanguages;
diff --git a/components/translate/core/browser/translate_ui_delegate_unittest.cc b/components/translate/core/browser/translate_ui_delegate_unittest.cc
index 0802bc4b2a472..80e7527ac3a2c 100644
--- a/components/translate/core/browser/translate_ui_delegate_unittest.cc
+++ b/components/translate/core/browser/translate_ui_delegate_unittest.cc
@@ -9,7 +9,6 @@
 #include "base/strings/utf_string_conversions.h"
 #include "base/test/scoped_feature_list.h"
 #include "build/build_config.h"
-#include "build/chromeos_buildflags.h"
 #include "components/infobars/core/infobar.h"
 #include "components/language/core/browser/language_model.h"
 #include "components/language/core/browser/language_prefs.h"
@@ -60,7 +59,7 @@ class TranslateUIDelegateTest : public ::testing::Test {
         std::make_unique<sync_preferences::TestingPrefServiceSyncable>();
     language::LanguagePrefs::RegisterProfilePrefs(pref_service_->registry());
     pref_service_->SetString(language::prefs::kAcceptLanguages, std::string());
-#if BUILDFLAG(IS_CHROMEOS_ASH)
+#if BUILDFLAG(IS_CHROMEOS)
     pref_service_->SetString(language::prefs::kPreferredLanguages,
                              std::string());
 #endif
diff --git a/components/translate/core/browser/translate_ui_languages_manager.cc b/components/translate/core/browser/translate_ui_languages_manager.cc
index ec6d94416daf2..f13457bf4027f 100644
--- a/components/translate/core/browser/translate_ui_languages_manager.cc
+++ b/components/translate/core/browser/translate_ui_languages_manager.cc
@@ -12,7 +12,6 @@
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/utf_string_conversions.h"
 #include "build/build_config.h"
-#include "build/chromeos_buildflags.h"
 #include "components/language/core/common/language_experiments.h"
 #include "components/strings/grit/components_strings.h"
 #include "components/translate/core/browser/language_state.h"
diff --git a/components/trusted_vault/BUILD.gn b/components/trusted_vault/BUILD.gn
index 97ee306415128..3a7565d12a1b2 100644
--- a/components/trusted_vault/BUILD.gn
+++ b/components/trusted_vault/BUILD.gn
@@ -146,20 +146,4 @@ static_library("test_support") {
       "//url",
     ]
   }
-
-  if (is_chromeos_lacros) {
-    sources += [
-      "test/fake_crosapi_trusted_vault_backend.cc",
-      "test/fake_crosapi_trusted_vault_backend.h",
-      "test/fake_crosapi_trusted_vault_backend_service.cc",
-      "test/fake_crosapi_trusted_vault_backend_service.h",
-    ]
-
-    public_deps += [
-      "//chromeos/crosapi/mojom",
-      "//mojo/public/cpp/bindings",
-    ]
-
-    deps += [ "//components/account_manager_core" ]
-  }
 }
diff --git a/components/trusted_vault/test/fake_crosapi_trusted_vault_backend.cc b/components/trusted_vault/test/fake_crosapi_trusted_vault_backend.cc
deleted file mode 100644
index b652b80dd4041..0000000000000
--- a/components/trusted_vault/test/fake_crosapi_trusted_vault_backend.cc
+++ /dev/null
@@ -1,139 +0,0 @@
-// Copyright 2023 The Chromium Authors
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#include "components/trusted_vault/test/fake_crosapi_trusted_vault_backend.h"
-
-#include <utility>
-
-#include "base/check.h"
-#include "chromeos/crosapi/mojom/account_manager.mojom.h"
-#include "components/account_manager_core/account.h"
-#include "components/account_manager_core/account_manager_util.h"
-
-namespace trusted_vault {
-
-FakeCrosapiTrustedVaultBackend::FakeCrosapiTrustedVaultBackend(
-    TrustedVaultClient* client)
-    : trusted_vault_client_(client) {
-  CHECK(trusted_vault_client_);
-  trusted_vault_client_->AddObserver(this);
-}
-
-FakeCrosapiTrustedVaultBackend::~FakeCrosapiTrustedVaultBackend() {
-  trusted_vault_client_->RemoveObserver(this);
-}
-
-void FakeCrosapiTrustedVaultBackend::BindReceiver(
-    mojo::PendingReceiver<crosapi::mojom::TrustedVaultBackend>
-        pending_receiver) {
-  receiver_.Bind(std::move(pending_receiver));
-}
-
-mojo::PendingRemote<crosapi::mojom::TrustedVaultBackend>
-FakeCrosapiTrustedVaultBackend::BindNewPipeAndPassRemote() {
-  return receiver_.BindNewPipeAndPassRemote();
-}
-
-void FakeCrosapiTrustedVaultBackend::FlushMojo() {
-  receiver_.FlushForTesting();
-  observer_.FlushForTesting();
-}
-
-void FakeCrosapiTrustedVaultBackend::SetPrimaryAccountInfo(
-    const CoreAccountInfo& primary_account_info) {
-  primary_account_info_ = primary_account_info;
-}
-
-void FakeCrosapiTrustedVaultBackend::OnTrustedVaultKeysChanged() {
-  if (observer_.is_bound()) {
-    observer_->OnTrustedVaultKeysChanged();
-  }
-}
-
-void FakeCrosapiTrustedVaultBackend::OnTrustedVaultRecoverabilityChanged() {
-  if (observer_.is_bound()) {
-    observer_->OnTrustedVaultRecoverabilityChanged();
-  }
-}
-
-void FakeCrosapiTrustedVaultBackend::AddObserver(
-    mojo::PendingRemote<crosapi::mojom::TrustedVaultBackendObserver> observer) {
-  observer_.Bind(std::move(observer));
-}
-
-void FakeCrosapiTrustedVaultBackend::FetchKeys(
-    crosapi::mojom::AccountKeyPtr account_key,
-    FetchKeysCallback callback) {
-  if (!ValidateAccountKeyIsPrimaryAccount(account_key)) {
-    std::move(callback).Run(std::vector<std::vector<uint8_t>>());
-    return;
-  }
-  trusted_vault_client_->FetchKeys(primary_account_info_, std::move(callback));
-}
-
-void FakeCrosapiTrustedVaultBackend::MarkLocalKeysAsStale(
-    crosapi::mojom::AccountKeyPtr account_key,
-    MarkLocalKeysAsStaleCallback callback) {
-  if (!ValidateAccountKeyIsPrimaryAccount(account_key)) {
-    std::move(callback).Run(false);
-    return;
-  }
-  trusted_vault_client_->MarkLocalKeysAsStale(primary_account_info_,
-                                              std::move(callback));
-}
-
-void FakeCrosapiTrustedVaultBackend::StoreKeys(
-    crosapi::mojom::AccountKeyPtr account_key,
-    const std::vector<std::vector<uint8_t>>& keys,
-    int32_t last_key_version) {
-  if (!ValidateAccountKeyIsPrimaryAccount(account_key)) {
-    return;
-  }
-  trusted_vault_client_->StoreKeys(primary_account_info_.gaia, keys,
-                                   last_key_version);
-}
-
-void FakeCrosapiTrustedVaultBackend::GetIsRecoverabilityDegraded(
-    crosapi::mojom::AccountKeyPtr account_key,
-    GetIsRecoverabilityDegradedCallback callback) {
-  if (!ValidateAccountKeyIsPrimaryAccount(account_key)) {
-    std::move(callback).Run(false);
-    return;
-  }
-  trusted_vault_client_->GetIsRecoverabilityDegraded(primary_account_info_,
-                                                     std::move(callback));
-}
-
-void FakeCrosapiTrustedVaultBackend::AddTrustedRecoveryMethod(
-    crosapi::mojom::AccountKeyPtr account_key,
-    const std::vector<uint8_t>& public_key,
-    int32_t method_type_hint,
-    AddTrustedRecoveryMethodCallback callback) {
-  if (!ValidateAccountKeyIsPrimaryAccount(account_key)) {
-    std::move(callback).Run();
-    return;
-  }
-  trusted_vault_client_->AddTrustedRecoveryMethod(primary_account_info_.gaia,
-                                                  public_key, method_type_hint,
-                                                  std::move(callback));
-}
-
-void FakeCrosapiTrustedVaultBackend::ClearLocalDataForAccount(
-    crosapi::mojom::AccountKeyPtr account_key) {
-  if (!ValidateAccountKeyIsPrimaryAccount(account_key)) {
-    return;
-  }
-  trusted_vault_client_->ClearLocalDataForAccount(primary_account_info_);
-}
-
-bool FakeCrosapiTrustedVaultBackend::ValidateAccountKeyIsPrimaryAccount(
-    const crosapi::mojom::AccountKeyPtr& mojo_account_key) const {
-  const std::optional<account_manager::AccountKey> account_key =
-      account_manager::FromMojoAccountKey(mojo_account_key);
-  return account_key.has_value() &&
-         account_key->account_type() == account_manager::AccountType::kGaia &&
-         account_key->id() == primary_account_info_.gaia;
-}
-
-}  // namespace trusted_vault
diff --git a/components/trusted_vault/test/fake_crosapi_trusted_vault_backend.h b/components/trusted_vault/test/fake_crosapi_trusted_vault_backend.h
deleted file mode 100644
index 21d62af80a6d1..0000000000000
--- a/components/trusted_vault/test/fake_crosapi_trusted_vault_backend.h
+++ /dev/null
@@ -1,74 +0,0 @@
-// Copyright 2023 The Chromium Authors
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#ifndef COMPONENTS_TRUSTED_VAULT_TEST_FAKE_CROSAPI_TRUSTED_VAULT_BACKEND_H_
-#define COMPONENTS_TRUSTED_VAULT_TEST_FAKE_CROSAPI_TRUSTED_VAULT_BACKEND_H_
-
-#include "chromeos/crosapi/mojom/account_manager.mojom-forward.h"
-#include "chromeos/crosapi/mojom/trusted_vault.mojom.h"
-#include "components/signin/public/identity_manager/account_info.h"
-#include "components/trusted_vault/trusted_vault_client.h"
-#include "mojo/public/cpp/bindings/pending_remote.h"
-#include "mojo/public/cpp/bindings/receiver.h"
-#include "mojo/public/cpp/bindings/remote.h"
-
-namespace trusted_vault {
-
-// Fake implementation of TrustedVaultBackend mojo interface, that allows to
-// test Lacros counterpart of counterpart (real implementation lives in Ash).
-class FakeCrosapiTrustedVaultBackend
-    : public crosapi::mojom::TrustedVaultBackend,
-      public TrustedVaultClient::Observer {
- public:
-  explicit FakeCrosapiTrustedVaultBackend(
-      TrustedVaultClient* client);
-  ~FakeCrosapiTrustedVaultBackend() override;
-
-  void BindReceiver(
-      mojo::PendingReceiver<crosapi::mojom::TrustedVaultBackend> receiver);
-  mojo::PendingRemote<crosapi::mojom::TrustedVaultBackend>
-  BindNewPipeAndPassRemote();
-  void FlushMojo();
-  void SetPrimaryAccountInfo(const CoreAccountInfo& primary_account_info);
-
-  // TrustedVaultClient::Observer implementation.
-  void OnTrustedVaultKeysChanged() override;
-  void OnTrustedVaultRecoverabilityChanged() override;
-
-  // crosapi::mojom::TrustedVaultBackend implementation.
-  void AddObserver(
-      mojo::PendingRemote<crosapi::mojom::TrustedVaultBackendObserver> observer)
-      override;
-  void FetchKeys(crosapi::mojom::AccountKeyPtr account_key,
-                 FetchKeysCallback callback) override;
-  void MarkLocalKeysAsStale(crosapi::mojom::AccountKeyPtr account_key,
-                            MarkLocalKeysAsStaleCallback callback) override;
-  void StoreKeys(crosapi::mojom::AccountKeyPtr account_key,
-                 const std::vector<std::vector<uint8_t>>& keys,
-                 int32_t last_key_version) override;
-  void GetIsRecoverabilityDegraded(
-      crosapi::mojom::AccountKeyPtr account_key,
-      GetIsRecoverabilityDegradedCallback callback) override;
-  void AddTrustedRecoveryMethod(
-      crosapi::mojom::AccountKeyPtr account_key,
-      const std::vector<uint8_t>& public_key,
-      int32_t method_type_hint,
-      AddTrustedRecoveryMethodCallback callback) override;
-  void ClearLocalDataForAccount(
-      crosapi::mojom::AccountKeyPtr account_key) override;
-
- private:
-  bool ValidateAccountKeyIsPrimaryAccount(
-      const crosapi::mojom::AccountKeyPtr& account_key) const;
-
-  CoreAccountInfo primary_account_info_;
-  const raw_ptr<TrustedVaultClient> trusted_vault_client_;
-
-  mojo::Receiver<crosapi::mojom::TrustedVaultBackend> receiver_{this};
-  mojo::Remote<crosapi::mojom::TrustedVaultBackendObserver> observer_;
-};
-
-}  // namespace trusted_vault
-
-#endif  // COMPONENTS_TRUSTED_VAULT_TEST_FAKE_CROSAPI_TRUSTED_VAULT_BACKEND_H_
diff --git a/components/trusted_vault/test/fake_crosapi_trusted_vault_backend_service.cc b/components/trusted_vault/test/fake_crosapi_trusted_vault_backend_service.cc
deleted file mode 100644
index 301f32954774c..0000000000000
--- a/components/trusted_vault/test/fake_crosapi_trusted_vault_backend_service.cc
+++ /dev/null
@@ -1,64 +0,0 @@
-// Copyright 2024 The Chromium Authors
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#include "components/trusted_vault/test/fake_crosapi_trusted_vault_backend_service.h"
-
-#include "base/check.h"
-#include "base/notreached.h"
-#include "chromeos/crosapi/mojom/account_manager.mojom.h"
-#include "chromeos/crosapi/mojom/trusted_vault.mojom.h"
-#include "components/trusted_vault/test/fake_crosapi_trusted_vault_backend.h"
-
-namespace trusted_vault {
-
-FakeCrosapiTrustedVaultBackendService::FakeCrosapiTrustedVaultBackendService(
-    TrustedVaultClient* chrome_sync_trusted_vault_client,
-    TrustedVaultClient* passkeys_trusted_vault_client)
-    : chrome_sync_trusted_vault_backend_(
-          std::make_unique<trusted_vault::FakeCrosapiTrustedVaultBackend>(
-              chrome_sync_trusted_vault_client)),
-      passkeys_trusted_vault_backend_(
-          std::make_unique<trusted_vault::FakeCrosapiTrustedVaultBackend>(
-              passkeys_trusted_vault_client)) {}
-
-FakeCrosapiTrustedVaultBackendService::
-    ~FakeCrosapiTrustedVaultBackendService() = default;
-
-void FakeCrosapiTrustedVaultBackendService::BindReceiver(
-    mojo::PendingReceiver<crosapi::mojom::TrustedVaultBackendService>
-        pending_receiver) {
-  receiver_.Bind(std::move(pending_receiver));
-}
-
-mojo::PendingRemote<crosapi::mojom::TrustedVaultBackendService>
-FakeCrosapiTrustedVaultBackendService::BindNewPipeAndPassRemote() {
-  return receiver_.BindNewPipeAndPassRemote();
-}
-
-FakeCrosapiTrustedVaultBackend&
-FakeCrosapiTrustedVaultBackendService::chrome_sync_backend() {
-  return *chrome_sync_trusted_vault_backend_;
-}
-
-FakeCrosapiTrustedVaultBackend&
-FakeCrosapiTrustedVaultBackendService::passkeys_backend() {
-  return *passkeys_trusted_vault_backend_;
-}
-
-void FakeCrosapiTrustedVaultBackendService::GetTrustedVaultBackend(
-    crosapi::mojom::SecurityDomainId security_domain,
-    mojo::PendingReceiver<crosapi::mojom::TrustedVaultBackend> backend) {
-  switch (security_domain) {
-    case crosapi::mojom::SecurityDomainId::kUnknown:
-      NOTREACHED();
-    case crosapi::mojom::SecurityDomainId::kChromeSync:
-      chrome_sync_trusted_vault_backend_->BindReceiver(std::move(backend));
-      break;
-    case crosapi::mojom::SecurityDomainId::kPasskeys:
-      passkeys_trusted_vault_backend_->BindReceiver(std::move(backend));
-      break;
-  }
-}
-
-}  // namespace trusted_vault
diff --git a/components/trusted_vault/test/fake_crosapi_trusted_vault_backend_service.h b/components/trusted_vault/test/fake_crosapi_trusted_vault_backend_service.h
deleted file mode 100644
index 774725b9dd6ac..0000000000000
--- a/components/trusted_vault/test/fake_crosapi_trusted_vault_backend_service.h
+++ /dev/null
@@ -1,55 +0,0 @@
-// Copyright 2024 The Chromium Authors
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#ifndef COMPONENTS_TRUSTED_VAULT_TEST_FAKE_CROSAPI_TRUSTED_VAULT_BACKEND_SERVICE_H_
-#define COMPONENTS_TRUSTED_VAULT_TEST_FAKE_CROSAPI_TRUSTED_VAULT_BACKEND_SERVICE_H_
-
-#include <memory>
-
-#include "chromeos/crosapi/mojom/trusted_vault.mojom.h"
-#include "components/trusted_vault/test/fake_crosapi_trusted_vault_backend.h"
-#include "components/trusted_vault/trusted_vault_client.h"
-#include "mojo/public/cpp/bindings/pending_remote.h"
-#include "mojo/public/cpp/bindings/receiver.h"
-#include "mojo/public/cpp/bindings/remote.h"
-
-namespace trusted_vault {
-
-// Fake implementation of TrustedVaultBackendService mojo interface, that allows
-// to test Lacros counterpart of counterpart (real implementation lives in Ash).
-class FakeCrosapiTrustedVaultBackendService
-    : public crosapi::mojom::TrustedVaultBackendService {
- public:
-  FakeCrosapiTrustedVaultBackendService(
-      TrustedVaultClient* chrome_sync_trusted_vault_client,
-      TrustedVaultClient* passkeys_trusted_vault_client);
-  ~FakeCrosapiTrustedVaultBackendService() override;
-
-  void BindReceiver(
-      mojo::PendingReceiver<crosapi::mojom::TrustedVaultBackendService>
-          receiver);
-  mojo::PendingRemote<crosapi::mojom::TrustedVaultBackendService>
-  BindNewPipeAndPassRemote();
-
-  FakeCrosapiTrustedVaultBackend& chrome_sync_backend();
-  FakeCrosapiTrustedVaultBackend& passkeys_backend();
-
-  // crosapi::mojom::TrustedVaultBackendService:
-  void GetTrustedVaultBackend(
-      crosapi::mojom::SecurityDomainId security_domain,
-      mojo::PendingReceiver<crosapi::mojom::TrustedVaultBackend> backend)
-      override;
-
- private:
-  std::unique_ptr<trusted_vault::FakeCrosapiTrustedVaultBackend>
-      chrome_sync_trusted_vault_backend_;
-  std::unique_ptr<trusted_vault::FakeCrosapiTrustedVaultBackend>
-      passkeys_trusted_vault_backend_;
-
-  mojo::Receiver<crosapi::mojom::TrustedVaultBackendService> receiver_{this};
-};
-
-}  // namespace trusted_vault
-
-#endif  // COMPONENTS_TRUSTED_VAULT_TEST_FAKE_CROSAPI_TRUSTED_VAULT_BACKEND_SERVICE_H_
diff --git a/components/unified_consent/BUILD.gn b/components/unified_consent/BUILD.gn
index 0a55ab85b8b3a..78759bc9cc24b 100644
--- a/components/unified_consent/BUILD.gn
+++ b/components/unified_consent/BUILD.gn
@@ -40,7 +40,6 @@ source_set("unit_tests") {
   deps = [
     ":unified_consent",
     "//base/test:test_support",
-    "//build:chromeos_buildflags",
     "//components/signin/public/identity_manager:test_support",
     "//components/sync:test_support",
     "//components/sync_preferences:test_support",
diff --git a/components/unified_consent/pref_names.cc b/components/unified_consent/pref_names.cc
index b71abb0238019..241b1974459b1 100644
--- a/components/unified_consent/pref_names.cc
+++ b/components/unified_consent/pref_names.cc
@@ -7,9 +7,9 @@
 namespace unified_consent {
 namespace prefs {
 
-#if BUILDFLAG(IS_CHROMEOS_ASH)
+#if BUILDFLAG(IS_CHROMEOS)
 const char kUnifiedConsentMigrationState[] = "unified_consent.migration_state";
-#endif  // BUILDFLAG(IS_CHROMEOS_ASH)
+#endif  // BUILDFLAG(IS_CHROMEOS)
 const char kUrlKeyedAnonymizedDataCollectionEnabled[] =
     "url_keyed_anonymized_data_collection.enabled";
 
diff --git a/components/unified_consent/pref_names.h b/components/unified_consent/pref_names.h
index b59514d1c8872..b4f65dc325916 100644
--- a/components/unified_consent/pref_names.h
+++ b/components/unified_consent/pref_names.h
@@ -6,11 +6,10 @@
 #define COMPONENTS_UNIFIED_CONSENT_PREF_NAMES_H_
 
 #include "build/build_config.h"
-#include "build/chromeos_buildflags.h"
 
 namespace unified_consent::prefs {
 
-#if BUILDFLAG(IS_CHROMEOS_ASH)
+#if BUILDFLAG(IS_CHROMEOS)
 // Integer indicating the migration state of unified consent, defined in
 // unified_consent::MigrationState.
 //
diff --git a/components/unified_consent/unified_consent_service.cc b/components/unified_consent/unified_consent_service.cc
index d90746c5ddd58..a8833b7e6e858 100644
--- a/components/unified_consent/unified_consent_service.cc
+++ b/components/unified_consent/unified_consent_service.cc
@@ -164,7 +164,7 @@ UnifiedConsentService::UnifiedConsentService(
   DCHECK(identity_manager_);
   DCHECK(sync_service_);
 
-#if BUILDFLAG(IS_CHROMEOS_ASH)
+#if BUILDFLAG(IS_CHROMEOS)
   if (GetMigrationState() == MigrationState::kNotInitialized)
     MigrateProfileToUnifiedConsent();
 #endif
@@ -186,7 +186,7 @@ void UnifiedConsentService::RegisterPrefs(
     user_prefs::PrefRegistrySyncable* registry) {
   registry->RegisterBooleanPref(prefs::kUrlKeyedAnonymizedDataCollectionEnabled,
                                 false);
-#if BUILDFLAG(IS_CHROMEOS_ASH)
+#if BUILDFLAG(IS_CHROMEOS)
   registry->RegisterIntegerPref(
       prefs::kUnifiedConsentMigrationState,
       static_cast<int>(MigrationState::kNotInitialized));
@@ -195,7 +195,7 @@ void UnifiedConsentService::RegisterPrefs(
 
 void UnifiedConsentService::SetUrlKeyedAnonymizedDataCollectionEnabled(
     bool enabled) {
-#if BUILDFLAG(IS_CHROMEOS_ASH)
+#if BUILDFLAG(IS_CHROMEOS)
   if (GetMigrationState() != MigrationState::kCompleted)
     SetMigrationState(MigrationState::kCompleted);
 #endif
@@ -267,7 +267,7 @@ void UnifiedConsentService::OnStateChanged(syncer::SyncService* sync) {
       service_pref_changes_.clear();
   }
 
-#if BUILDFLAG(IS_CHROMEOS_ASH)
+#if BUILDFLAG(IS_CHROMEOS)
   // TODO(crbug.com/40066949): Simplify (remove the following block) after
   // Sync-the-feature users are migrated to ConsentLevel::kSignin (and thus
   // CanSyncFeatureStart() always returns false).
@@ -317,7 +317,7 @@ void UnifiedConsentService::ServicePrefChanged(const std::string& name) {
   service_pref_changes_[name] = value.Clone();
 }
 
-#if BUILDFLAG(IS_CHROMEOS_ASH)
+#if BUILDFLAG(IS_CHROMEOS)
 MigrationState UnifiedConsentService::GetMigrationState() {
   int migration_state_int =
       pref_service_->GetInteger(prefs::kUnifiedConsentMigrationState);
@@ -365,6 +365,6 @@ void UnifiedConsentService::UpdateSettingsForMigration() {
       !sync_service_->GetUserSettings()->IsUsingExplicitPassphrase();
   SetUrlKeyedAnonymizedDataCollectionEnabled(url_keyed_metrics_enabled);
 }
-#endif  // BUILDFLAG(IS_CHROMEOS_ASH)
+#endif  // BUILDFLAG(IS_CHROMEOS)
 
 }  //  namespace unified_consent
diff --git a/components/unified_consent/unified_consent_service.h b/components/unified_consent/unified_consent_service.h
index 12c1e97e57625..c9281536ac5ad 100644
--- a/components/unified_consent/unified_consent_service.h
+++ b/components/unified_consent/unified_consent_service.h
@@ -32,14 +32,14 @@ class SyncService;
 
 namespace unified_consent {
 
-#if BUILDFLAG(IS_CHROMEOS_ASH)
+#if BUILDFLAG(IS_CHROMEOS)
 enum class MigrationState : int {
   kNotInitialized = 0,
   kInProgressWaitForSyncInit = 1,
   // Reserve space for other kInProgress* entries to be added here.
   kCompleted = 10,
 };
-#endif  // BUILDFLAG(IS_CHROMEOS_ASH)
+#endif  // BUILDFLAG(IS_CHROMEOS)
 
 // A browser-context keyed service that is used to manage the user consent
 // when UnifiedConsent feature is enabled.
@@ -127,7 +127,7 @@ class UnifiedConsentService
   void StopObservingServicePrefChanges();
   void ServicePrefChanged(const std::string& name);
 
-#if BUILDFLAG(IS_CHROMEOS_ASH)
+#if BUILDFLAG(IS_CHROMEOS)
   // Migration helpers.
   MigrationState GetMigrationState();
   void SetMigrationState(MigrationState migration_state);
diff --git a/components/unified_consent/unified_consent_service_unittest.cc b/components/unified_consent/unified_consent_service_unittest.cc
index 7291b5cfcb9a3..f07ed97aaa81e 100644
--- a/components/unified_consent/unified_consent_service_unittest.cc
+++ b/components/unified_consent/unified_consent_service_unittest.cc
@@ -13,7 +13,6 @@
 #include "base/test/scoped_feature_list.h"
 #include "base/test/task_environment.h"
 #include "build/build_config.h"
-#include "build/chromeos_buildflags.h"
 #include "components/signin/public/identity_manager/identity_test_environment.h"
 #include "components/sync/base/features.h"
 #include "components/sync/base/user_selectable_type.h"
@@ -91,7 +90,7 @@ class UnifiedConsentServiceTest : public testing::Test {
     }
   }
 
-#if BUILDFLAG(IS_CHROMEOS_ASH)
+#if BUILDFLAG(IS_CHROMEOS)
   unified_consent::MigrationState GetMigrationState() {
     int migration_state_int =
         pref_service_.GetInteger(prefs::kUnifiedConsentMigrationState);
@@ -199,7 +198,7 @@ TEST_F(UnifiedConsentServiceTest, ReplaceSync_HistorySyncIgnoredForSyncUsers) {
       prefs::kUrlKeyedAnonymizedDataCollectionEnabled));
 }
 
-#if !BUILDFLAG(IS_CHROMEOS_ASH)
+#if !BUILDFLAG(IS_CHROMEOS)
 // Tests that kUrlKeyedAnonymizedDataCollectionEnabled is enabled after
 // syncing user signs out, then in again and enabled history sync opt-in.
 TEST_F(UnifiedConsentServiceTest,
@@ -238,7 +237,7 @@ TEST_F(UnifiedConsentServiceTest,
   EXPECT_FALSE(pref_service()->GetBoolean(
       prefs::kUrlKeyedAnonymizedDataCollectionEnabled));
 }
-#endif  // !BUILDFLAG(IS_CHROMEOS_ASH)
+#endif  // !BUILDFLAG(IS_CHROMEOS)
 
 // Tests that any change to history sync opt-in, is reflected in the state
 // of `kUrlKeyedAnonymizedDataCollectionEnabled`.
@@ -361,7 +360,7 @@ TEST_F(UnifiedConsentServiceTest, ReplaceSync_StateTransitions) {
   }
 }
 
-#if BUILDFLAG(IS_CHROMEOS_ASH)
+#if BUILDFLAG(IS_CHROMEOS)
 TEST_F(UnifiedConsentServiceTest, Migration_UpdateSettings) {
   // Create user that syncs history and has no custom passphrase.
   SignIn(signin::ConsentLevel::kSync);
@@ -402,6 +401,6 @@ TEST_F(UnifiedConsentServiceTest, ClearPrimaryAccountDisablesSomeServices) {
   EXPECT_FALSE(pref_service()->GetBoolean(
       prefs::kUrlKeyedAnonymizedDataCollectionEnabled));
 }
-#endif  // BUILDFLAG(IS_CHROMEOS_ASH)
+#endif  // BUILDFLAG(IS_CHROMEOS)
 
 }  // namespace unified_consent
diff --git a/components/update_client/BUILD.gn b/components/update_client/BUILD.gn
index 3f795f9a49681..aa23adbe74a3c 100644
--- a/components/update_client/BUILD.gn
+++ b/components/update_client/BUILD.gn
@@ -65,7 +65,6 @@ source_set("patch_impl") {
   ]
   deps = [
     ":update_client",
-    "//build:chromeos_buildflags",
     "//components/services/patch/public/cpp",
     "//components/services/patch/public/mojom",
     "//mojo/public/cpp/bindings",
@@ -163,7 +162,6 @@ static_library("update_client") {
   deps = [
     "//base",
     "//build:branding_buildflags",
-    "//build:chromeos_buildflags",
     "//components/client_update_protocol",
     "//components/crx_file",
     "//components/prefs",
diff --git a/components/update_client/update_query_params.cc b/components/update_client/update_query_params.cc
index 1a8b4459fca5c..b1701d056cb05 100644
--- a/components/update_client/update_query_params.cc
+++ b/components/update_client/update_query_params.cc
@@ -9,7 +9,6 @@
 #include "base/system/sys_info.h"
 #include "build/branding_buildflags.h"
 #include "build/build_config.h"
-#include "build/chromeos_buildflags.h"
 #include "components/update_client/update_query_params_delegate.h"
 #include "components/version_info/version_info.h"
 
@@ -34,7 +33,7 @@ const char kOs[] =
     "android";
 #elif BUILDFLAG(IS_CHROMEOS)
     "cros";
-#elif BUILDFLAG(IS_LINUX) || BUILDFLAG(IS_CHROMEOS_LACROS)
+#elif BUILDFLAG(IS_LINUX)
     "linux";
 #elif BUILDFLAG(IS_FUCHSIA)
     "fuchsia";
diff --git a/components/user_manager/BUILD.gn b/components/user_manager/BUILD.gn
index 1453abeb852b1..ad904ecea7e9a 100644
--- a/components/user_manager/BUILD.gn
+++ b/components/user_manager/BUILD.gn
@@ -2,8 +2,6 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-import("//build/config/chromeos/ui_mode.gni")
-
 component("common") {
   sources = [
     "user_type.cc",
@@ -41,7 +39,7 @@ component("user_manager") {
 
   defines = [ "USER_MANAGER_IMPLEMENTATION" ]
 
-  if (is_chromeos_ash) {
+  if (is_chromeos) {
     sources += [
       "account_id_util.cc",
       "account_id_util.h",
@@ -82,7 +80,7 @@ component("user_manager") {
   }
 }
 
-if (is_chromeos_ash) {
+if (is_chromeos) {
   source_set("test_support") {
     testonly = true
     sources = [
diff --git a/components/vector_icons/BUILD.gn b/components/vector_icons/BUILD.gn
index 1dcab778676a6..2d20fe5a82e35 100644
--- a/components/vector_icons/BUILD.gn
+++ b/components/vector_icons/BUILD.gn
@@ -2,7 +2,6 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-import("//build/config/chromeos/ui_mode.gni")
 import("//build/util/branding.gni")
 import("//components/vector_icons/vector_icons.gni")
 
@@ -259,11 +258,10 @@ aggregate_vector_icons("components_vector_icons") {
   ]
 
   if (is_chromeos) {
-    sources += [ "notification_download.icon" ]
-  }
-
-  if (is_chromeos_ash) {
-    sources += [ "videogame_asset_outline.icon" ]
+    sources += [
+      "notification_download.icon",
+      "videogame_asset_outline.icon",
+    ]
   }
 
   if (is_chrome_branded) {
diff --git a/components/version_ui/BUILD.gn b/components/version_ui/BUILD.gn
index 913cf913dca7a..49f73fb885870 100644
--- a/components/version_ui/BUILD.gn
+++ b/components/version_ui/BUILD.gn
@@ -12,7 +12,6 @@ static_library("version_ui") {
 
   deps = [
     "//base",
-    "//build:chromeos_buildflags",
     "//components/variations",
     "//components/variations/net",
     "//components/variations/service",
diff --git a/components/version_ui/version_ui_constants.cc b/components/version_ui/version_ui_constants.cc
index 1054d152285f7..a4677847706a6 100644
--- a/components/version_ui/version_ui_constants.cc
+++ b/components/version_ui/version_ui_constants.cc
@@ -5,7 +5,6 @@
 #include "components/version_ui/version_ui_constants.h"
 
 #include "build/build_config.h"
-#include "build/chromeos_buildflags.h"
 
 namespace version_ui {
 
@@ -49,7 +48,7 @@ const char kJSVersion[] = "js_version";
 #endif
 const char kLogoAltText[] = "logo_alt_text";
 const char kOfficial[] = "official";
-#if !BUILDFLAG(IS_CHROMEOS_ASH)
+#if !BUILDFLAG(IS_CHROMEOS)
 const char kOSName[] = "os_name";
 const char kOSType[] = "os_type";
 #endif
diff --git a/components/version_ui/version_ui_constants.h b/components/version_ui/version_ui_constants.h
index 0d35047553461..5d43d7626b3c3 100644
--- a/components/version_ui/version_ui_constants.h
+++ b/components/version_ui/version_ui_constants.h
@@ -6,7 +6,6 @@
 #define COMPONENTS_VERSION_UI_VERSION_UI_CONSTANTS_H_
 
 #include "build/build_config.h"
-#include "build/chromeos_buildflags.h"
 
 namespace version_ui {
 
@@ -51,7 +50,7 @@ extern const char kJSVersion[];
 #endif
 extern const char kLogoAltText[];
 extern const char kOfficial[];
-#if !BUILDFLAG(IS_CHROMEOS_ASH)
+#if !BUILDFLAG(IS_CHROMEOS)
 extern const char kOSName[];
 extern const char kOSType[];
 #endif
diff --git a/components/web_resource/BUILD.gn b/components/web_resource/BUILD.gn
index b9fc4bfa19103..ab73617524a74 100644
--- a/components/web_resource/BUILD.gn
+++ b/components/web_resource/BUILD.gn
@@ -15,7 +15,6 @@ static_library("web_resource") {
   deps = [
     "//base",
     "//build:branding_buildflags",
-    "//build:chromeos_buildflags",
     "//components/pref_registry",
     "//components/prefs",
     "//services/network/public/cpp",
diff --git a/components/web_resource/eula_accepted_notifier.cc b/components/web_resource/eula_accepted_notifier.cc
index 23cb39cfc197e..ac78d2f6f7594 100644
--- a/components/web_resource/eula_accepted_notifier.cc
+++ b/components/web_resource/eula_accepted_notifier.cc
@@ -8,7 +8,6 @@
 #include "base/functional/bind.h"
 #include "build/branding_buildflags.h"
 #include "build/build_config.h"
-#include "build/chromeos_buildflags.h"
 #include "components/prefs/pref_service.h"
 #include "components/web_resource/web_resource_pref_names.h"
 
@@ -44,7 +43,7 @@ bool EulaAcceptedNotifier::IsEulaAccepted() {
 EulaAcceptedNotifier* EulaAcceptedNotifier::Create(PrefService* local_state) {
 // First run EULA only exists on ChromeOS, Android and iOS. On ChromeOS, it is
 // only shown in official builds.
-#if (BUILDFLAG(IS_CHROMEOS_ASH) && BUILDFLAG(GOOGLE_CHROME_BRANDING)) || \
+#if (BUILDFLAG(IS_CHROMEOS) && BUILDFLAG(GOOGLE_CHROME_BRANDING)) || \
     BUILDFLAG(IS_ANDROID) || BUILDFLAG(IS_IOS)
   // Tests that use higher-level classes that use EulaAcceptNotifier may not
   // have local state or may not register this pref. Return null to indicate not