Introduce UserManagerBase::Delegate.

As explicit injection point, instead of inheritance.
As a first step. GetApplicationLocale().

BUG=278643115
TEST=Tryjob

Change-Id: Ice88e29acdb463f38de4e0985640e6de36f14ba5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5387484
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Commit-Queue: Hidehiko Abe <hidehiko@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1277744}

chrome/browser/ash/BUILD.gn

@@ -2198,6 +2198,8 @@ source_set("ash") {
     "login/users/default_user_image/default_user_images.h",
     "login/users/test_users.cc",
     "login/users/test_users.h",
+    "login/users/user_manager_delegate_impl.cc",
+    "login/users/user_manager_delegate_impl.h",
     "login/version_info_updater.cc",
     "login/version_info_updater.h",
     "login/version_updater/update_time_estimator.cc",

chrome/browser/ash/login/users/chrome_user_manager_impl.cc

@@ -46,6 +46,7 @@
 #include "chrome/browser/ash/login/users/affiliation.h"
 #include "chrome/browser/ash/login/users/chrome_user_manager_util.h"
 #include "chrome/browser/ash/login/users/default_user_image/default_user_images.h"
+#include "chrome/browser/ash/login/users/user_manager_delegate_impl.h"
 #include "chrome/browser/ash/policy/core/browser_policy_connector_ash.h"
 #include "chrome/browser/ash/policy/core/device_local_account.h"
 #include "chrome/browser/ash/policy/external_data/handlers/crostini_ansible_playbook_external_data_handler.h"
@@ -290,6 +291,7 @@ ChromeUserManagerImpl::CreateChromeUserManager() {
 
 ChromeUserManagerImpl::ChromeUserManagerImpl()
     : UserManagerBase(
+          std::make_unique<UserManagerDelegateImpl>(),
           base::SingleThreadTaskRunner::HasCurrentDefault()
               ? base::SingleThreadTaskRunner::GetCurrentDefault()
               : nullptr,
@@ -591,10 +593,6 @@ void ChromeUserManagerImpl::OnDeviceLocalAccountsChanged() {
   // handled via the kAccountsPrefDeviceLocalAccounts device setting observer.
 }
 
-const std::string& ChromeUserManagerImpl::GetApplicationLocale() const {
-  return g_browser_process->GetApplicationLocale();
-}
-
 bool ChromeUserManagerImpl::IsEnterpriseManaged() const {
   policy::BrowserPolicyConnectorAsh* connector =
       g_browser_process->platform_part()->browser_policy_connector_ash();

chrome/browser/ash/login/users/chrome_user_manager_impl.h

@@ -117,7 +117,6 @@ class ChromeUserManagerImpl
   void OnProfileWillBeDestroyed(Profile* profile) override;
 
  protected:
-  const std::string& GetApplicationLocale() const override;
   void LoadDeviceLocalAccounts(std::set<AccountId>* users_set) override;
   void NotifyOnLogin() override;
   void NotifyUserAddedToSession(const user_manager::User* added_user,

chrome/browser/ash/login/users/fake_chrome_user_manager.cc

@@ -24,6 +24,7 @@
 #include "chrome/test/base/testing_profile.h"
 #include "chromeos/ash/components/login/login_state/login_state.h"
 #include "components/user_manager/fake_user_manager.h"
+#include "components/user_manager/fake_user_manager_delegate.h"
 #include "components/user_manager/known_user.h"
 #include "components/user_manager/multi_user/multi_user_sign_in_policy_controller.h"
 #include "components/user_manager/user.h"
@@ -69,6 +70,7 @@ namespace ash {
 
 FakeChromeUserManager::FakeChromeUserManager()
     : UserManagerBase(
+          std::make_unique<user_manager::FakeUserManagerDelegate>(),
           new FakeTaskRunner(),
           g_browser_process ? g_browser_process->local_state() : nullptr) {
   ProfileHelper::SetProfileToUserForTestingEnabled(true);
@@ -565,11 +567,6 @@ void FakeChromeUserManager::SimulateUserProfileLoad(
   }
 }
 
-const std::string& FakeChromeUserManager::GetApplicationLocale() const {
-  static const std::string default_locale("en-US");
-  return default_locale;
-}
-
 void FakeChromeUserManager::LoadDeviceLocalAccounts(
     std::set<AccountId>* users_set) {
   NOTREACHED();

chrome/browser/ash/login/users/fake_chrome_user_manager.h

@@ -131,7 +131,6 @@ class FakeChromeUserManager : public user_manager::UserManagerBase {
   GetMultiUserSignInPolicyController() override;
 
   // user_manager::UserManagerBase override.
-  const std::string& GetApplicationLocale() const override;
   void LoadDeviceLocalAccounts(std::set<AccountId>* users_set) override;
   bool IsEnterpriseManaged() const override;
   void PerformPostUserLoggedInActions(bool browser_restart) override;

chrome/browser/ash/login/users/user_manager_delegate_impl.cc

@@ -0,0 +1,18 @@
+// 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 "chrome/browser/ash/login/users/user_manager_delegate_impl.h"
+
+#include "chrome/browser/browser_process.h"
+
+namespace ash {
+
+UserManagerDelegateImpl::UserManagerDelegateImpl() = default;
+UserManagerDelegateImpl::~UserManagerDelegateImpl() = default;
+
+const std::string& UserManagerDelegateImpl::GetApplicationLocale() {
+  return g_browser_process->GetApplicationLocale();
+}
+
+}  // namespace ash

chrome/browser/ash/login/users/user_manager_delegate_impl.h

@@ -0,0 +1,26 @@
+// 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 CHROME_BROWSER_ASH_LOGIN_USERS_USER_MANAGER_DELEGATE_IMPL_H_
+#define CHROME_BROWSER_ASH_LOGIN_USERS_USER_MANAGER_DELEGATE_IMPL_H_
+
+#include "components/user_manager/user_manager_base.h"
+
+namespace ash {
+
+// Implementation of UserManagerBase::Delegate to inject //chrome/* behavior.
+class UserManagerDelegateImpl : public user_manager::UserManagerBase::Delegate {
+ public:
+  UserManagerDelegateImpl();
+  UserManagerDelegateImpl(const UserManagerDelegateImpl&) = delete;
+  UserManagerDelegateImpl& operator=(const UserManagerDelegateImpl&) = delete;
+  ~UserManagerDelegateImpl() override;
+
+  // UserManagerBase::Delegate:
+  const std::string& GetApplicationLocale() override;
+};
+
+}  // namespace ash
+
+#endif  // CHROME_BROWSER_ASH_LOGIN_USERS_USER_MANAGER_DELEGATE_IMPL_H_

components/user_manager/BUILD.gn

@@ -77,6 +77,8 @@ if (is_chromeos_ash) {
       "fake_device_ownership_waiter.h",
       "fake_user_manager.cc",
       "fake_user_manager.h",
+      "fake_user_manager_delegate.cc",
+      "fake_user_manager_delegate.h",
     ]
 
     public_deps = [

components/user_manager/fake_user_manager.cc

@@ -11,6 +11,7 @@
 #include "base/ranges/algorithm.h"
 #include "base/system/sys_info.h"
 #include "base/task/single_thread_task_runner.h"
+#include "components/user_manager/fake_user_manager_delegate.h"
 #include "components/user_manager/user_names.h"
 #include "components/user_manager/user_type.h"
 
@@ -41,7 +42,9 @@ class FakeTaskRunner : public base::SingleThreadTaskRunner {
 namespace user_manager {
 
 FakeUserManager::FakeUserManager(PrefService* local_state)
-    : UserManagerBase(new FakeTaskRunner(), local_state) {}
+    : UserManagerBase(std::make_unique<FakeUserManagerDelegate>(),
+                      new FakeTaskRunner(),
+                      local_state) {}
 
 FakeUserManager::~FakeUserManager() = default;
 
@@ -356,11 +359,6 @@ bool FakeUserManager::IsEphemeralAccountIdByPolicy(
   return GetEphemeralModeConfig().IsAccountIdIncluded(account_id);
 }
 
-const std::string& FakeUserManager::GetApplicationLocale() const {
-  static const std::string default_locale("en-US");
-  return default_locale;
-}
-
 bool FakeUserManager::IsEnterpriseManaged() const {
   return false;
 }

components/user_manager/fake_user_manager.h

@@ -126,7 +126,6 @@ class USER_MANAGER_EXPORT FakeUserManager : public UserManagerBase {
   void SetEphemeralModeConfig(
       EphemeralModeConfig ephemeral_mode_config) override;
 
-  const std::string& GetApplicationLocale() const override;
   bool IsEnterpriseManaged() const override;
   void LoadDeviceLocalAccounts(
       std::set<AccountId>* device_local_accounts_set) override {}

components/user_manager/fake_user_manager_delegate.cc

@@ -0,0 +1,21 @@
+// 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/user_manager/fake_user_manager_delegate.h"
+
+#include <string>
+
+#include "base/no_destructor.h"
+
+namespace user_manager {
+
+FakeUserManagerDelegate::FakeUserManagerDelegate() = default;
+FakeUserManagerDelegate::~FakeUserManagerDelegate() = default;
+
+const std::string& FakeUserManagerDelegate::GetApplicationLocale() {
+  static const base::NoDestructor<std::string> default_locale("en-US");
+  return *default_locale;
+}
+
+}  // namespace user_manager

components/user_manager/fake_user_manager_delegate.h

@@ -0,0 +1,28 @@
+// 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_USER_MANAGER_FAKE_USER_MANAGER_DELEGATE_H_
+#define COMPONENTS_USER_MANAGER_FAKE_USER_MANAGER_DELEGATE_H_
+
+#include "components/user_manager/user_manager_base.h"
+#include "components/user_manager/user_manager_export.h"
+
+namespace user_manager {
+
+// Fake implementation of UserManagerBase::Delegate.
+class USER_MANAGER_EXPORT FakeUserManagerDelegate
+    : public UserManagerBase::Delegate {
+ public:
+  FakeUserManagerDelegate();
+  FakeUserManagerDelegate(const FakeUserManagerDelegate&) = delete;
+  FakeUserManagerDelegate& operator=(const FakeUserManagerDelegate&) = delete;
+  ~FakeUserManagerDelegate() override;
+
+  // UserManagerBase::Delegate:
+  const std::string& GetApplicationLocale() override;
+};
+
+}  // namespace user_manager
+
+#endif  // COMPONENTS_USER_MANAGER_FAKE_USER_MANAGER_DELEGATE_H_

components/user_manager/user_manager_base.cc

@@ -109,9 +109,12 @@ void UserManagerBase::RegisterPrefs(PrefRegistrySimple* registry) {
 }
 
 UserManagerBase::UserManagerBase(
+    std::unique_ptr<Delegate> delegate,
     scoped_refptr<base::SingleThreadTaskRunner> task_runner,
     PrefService* local_state)
-    : task_runner_(std::move(task_runner)), local_state_(local_state) {
+    : delegate_(std::move(delegate)),
+      task_runner_(std::move(task_runner)),
+      local_state_(local_state) {
   // |local_state| can be nullptr only for testing.
   if (!local_state) {
     CHECK_IS_TEST();
@@ -1357,7 +1360,7 @@ void UserManagerBase::SendGaiaUserLoginMetrics(const AccountId& account_id) {
 void UserManagerBase::UpdateUserAccountLocale(const AccountId& account_id,
                                               const std::string& locale) {
   std::unique_ptr<std::string> resolved_locale(new std::string());
-  if (!locale.empty() && locale != GetApplicationLocale()) {
+  if (!locale.empty() && locale != delegate_->GetApplicationLocale()) {
     // std::move will nullptr out |resolved_locale|, so cache the underlying
     // ptr.
     std::string* raw_resolved_locale = resolved_locale.get();

components/user_manager/user_manager_base.h

@@ -64,9 +64,22 @@ class USER_MANAGER_EXPORT UserManagerBase : public UserManager {
     kMaxValue = kLSUDeleted
   };
 
+  // Delegate interface to inject //chrome/* dependency.
+  // In case you need to extend this, please consider to minimize the
+  // responsibility, because it means to depend more things on //chrome/*
+  // browser from ash-system, which we prefer minimizing.
+  class Delegate {
+   public:
+    virtual ~Delegate() = default;
+
+    // Returns the application locale.
+    virtual const std::string& GetApplicationLocale() = 0;
+  };
+
   // Creates UserManagerBase with |task_runner| for UI thread, and given
   // |local_state|. |local_state| must outlive this UserManager.
-  UserManagerBase(scoped_refptr<base::SingleThreadTaskRunner> task_runner,
+  UserManagerBase(std::unique_ptr<Delegate> delegate,
+                  scoped_refptr<base::SingleThreadTaskRunner> task_runner,
                   PrefService* local_state);
 
   UserManagerBase(const UserManagerBase&) = delete;
@@ -203,9 +216,6 @@ class USER_MANAGER_EXPORT UserManagerBase : public UserManager {
   // equals to active_user_, active_user_ is reset to NULL.
   virtual void DeleteUser(User* user);
 
-  // Returns the locale used by the application.
-  virtual const std::string& GetApplicationLocale() const = 0;
-
   // Loads |users_| from Local State if the list has not been loaded yet.
   // Subsequent calls have no effect. Must be called on the UI thread.
   virtual void EnsureUsersLoaded();
@@ -381,6 +391,8 @@ class USER_MANAGER_EXPORT UserManagerBase : public UserManager {
 
   void RemoveLegacySupervisedUser(const AccountId& account_id);
 
+  std::unique_ptr<Delegate> delegate_;
+
   // Indicates stage of loading user from prefs.
   UserLoadStage user_loading_stage_ = STAGE_NOT_LOADED;