Make tvOS imply iOS in GN and C++/Objective-C++

Following recent conversations with relevant Chromium on iOS folks, it
was decided that it made more sense for now to reverse one of the
decisions from https://crrev.com/c/6197019 and stop making the tvOS and
iOS builds be completely independent of each other: having them be
completely separate would require too many changes in GN, .grd, .py and
C++/Objective-C++ files in the tree (and even more so if we started
renaming the _ios.{mm,cc,h} files to something more generic).

More succinctly, this means that IS_IOS_TVOS in C++ and
`target_platform` in GN are set if and only if IS_IOS and is_ios are set
too, and iOS files and code paths are built on tvOS by default (rather
than being opt-in).

This CL implements this reversal while also making a few more
adjustments:

* The `is_tvos` GN flag is now called `target_platform` and takes
  "iphoneos" (default), "tvos" or "watchos" as values at the moment. As
  mentioned, it is set only if `is_ios` is also true (i.e. the target
  toolchain is being used). Files used by multiple toolchains may need
  to check for `is_ios` as well before referencing it.
* The GN flag is no longer being set in the main BUILDCONFIG.gn file,
  but rather in one of the files in //build/config/apple. Build system
  files that need to check this variable need to explicitly import this
  file.
* `BUILDFLAG(IS_TVOS)` is now `BUILDFLAG(IS_IOS_TVOS)` in C++.

Bug: 391990604, 391914246, 397889862
Change-Id: I7862cf63074b8ff75b4b58c911212d4652cae113
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6306066
Reviewed-by: Nico Weber <thakis@chromium.org>
Reviewed-by: Dave Tapuska <dtapuska@chromium.org>
Commit-Queue: Raphael Kubo da Costa <kubo@igalia.com>
Reviewed-by: Colin Blundell <blundell@chromium.org>
Reviewed-by: Sylvain Defresne <sdefresne@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1426638}

base/BUILD.gn

@@ -45,7 +45,7 @@ import("//testing/libfuzzer/fuzzer_test.gni")
 import("//testing/test.gni")
 
 if (is_ios) {
-  # Used to access target_environment.
+  # Used to access target_environment and target_platform.
   import("//build/config/apple/mobile_config.gni")
 
   # Used to access ios_is_app_extension variable definition.
@@ -2188,13 +2188,20 @@ component("base") {
         "process/process_handle_mac.cc",
         "process/process_ios.cc",
         "process/process_iterator_mac.cc",
-        "process/process_mac.cc",
         "process/process_posix.cc",
         "sync_socket_posix.cc",
         "synchronization/waitable_event_posix.cc",
         "synchronization/waitable_event_watcher_posix.cc",
       ]
 
+      if (target_platform == "tvos") {
+        # tvOS apps must be single-process. Build a Process version that does
+        # the bare minimum and does not use Mach ports.
+        sources += [ "process/process_tvos.cc" ]
+      } else {
+        sources += [ "process/process_mac.cc" ]
+      }
+
       # We include launch_mac on simulator builds so unittests can fork.
       if (target_environment == "simulator") {
         sources += [
@@ -2252,13 +2259,6 @@ component("base") {
     ]
   }
 
-  # tvOS.
-  if (is_tvos) {
-    sources -= [ "process/process_mac.cc" ]
-
-    sources += [ "process/process_tvos.cc" ]
-  }
-
   # Linux.
   if (is_linux || is_chromeos) {
     # TODO(brettw) this will need to be parameterized at some point.

base/process/process.h

@@ -222,7 +222,7 @@ class BASE_EXPORT Process {
   };
 
 #if (BUILDFLAG(IS_MAC) || (BUILDFLAG(IS_IOS) && BUILDFLAG(USE_BLINK))) && \
-    !BUILDFLAG(IS_TVOS)
+    !BUILDFLAG(IS_IOS_TVOS)
   // The Mac needs a Mach port in order to manipulate a process's priority,
   // and there's no good way to get that from base given the pid. These Mac
   // variants of the `GetPriority()` and `SetPriority()` API take a port

build/build_config.h

@@ -16,10 +16,10 @@
 //
 //  Operating System:
 //    IS_AIX / IS_ANDROID / IS_ASMJS / IS_CHROMEOS / IS_FREEBSD / IS_FUCHSIA /
-//    IS_IOS / IS_IOS_MACCATALYST / IS_LINUX / IS_MAC / IS_NACL / IS_NETBSD /
-//    IS_OPENBSD / IS_QNX / IS_SOLARIS / IS_TVOS / IS_WATCHOS / IS_WIN
+//    IS_IOS / IS_IOS_MACCATALYST / IS_IOS_TVOS / IS_LINUX / IS_MAC / IS_NACL /
+//    IS_NETBSD / IS_OPENBSD / IS_QNX / IS_SOLARIS / IS_WATCHOS / IS_WIN
 //  Operating System family:
-//    IS_APPLE: IOS or MAC or IOS_MACCATALYST or TVOS or WATCHOS
+//    IS_APPLE: IOS or MAC or IOS_MACCATALYST or IOS_TVOS or WATCHOS
 //    IS_BSD: FREEBSD or NETBSD or OPENBSD
 //    IS_POSIX: AIX or ANDROID or ASMJS or CHROMEOS or FREEBSD or IOS or LINUX
 //              or MAC or NACL or NETBSD or OPENBSD or QNX or SOLARIS
@@ -78,7 +78,7 @@
 #define OS_IOS_MACCATALYST
 #endif  // defined(TARGET_OS_MACCATALYST) && TARGET_OS_MACCATALYST
 #if defined(TARGET_OS_TV) && TARGET_OS_TV
-#define OS_TVOS 1
+#define OS_IOS_TVOS 1
 #endif  // defined(TARGET_OS_TV) && TARGET_OS_TV
 #if defined(TARGET_OS_WATCH) && TARGET_OS_WATCH
 #define OS_WATCHOS 1
@@ -205,6 +205,12 @@
 #define BUILDFLAG_INTERNAL_IS_IOS_MACCATALYST() (0)
 #endif
 
+#if defined(OS_IOS_TVOS)
+#define BUILDFLAG_INTERNAL_IS_IOS_TVOS() (1)
+#else
+#define BUILDFLAG_INTERNAL_IS_IOS_TVOS() (0)
+#endif
+
 #if defined(OS_LINUX)
 #define BUILDFLAG_INTERNAL_IS_LINUX() (1)
 #else
@@ -253,12 +259,6 @@
 #define BUILDFLAG_INTERNAL_IS_SOLARIS() (0)
 #endif
 
-#if defined(OS_TVOS)
-#define BUILDFLAG_INTERNAL_IS_TVOS() (1)
-#else
-#define BUILDFLAG_INTERNAL_IS_TVOS() (0)
-#endif
-
 #if defined(OS_WATCHOS)
 #define BUILDFLAG_INTERNAL_IS_WATCHOS() (1)
 #else

build/config/BUILDCONFIG.gn

@@ -170,15 +170,13 @@ declare_args() {
   #
   # For more information see
   # https://chromium.googlesource.com/chromium/src/+/main/docs/component_build.md
-  is_component_build = is_debug && current_os != "ios" &&
-                       current_os != "tvos" && current_os != "watchos"
+  is_component_build =
+      is_debug && current_os != "ios" && current_os != "watchos"
 }
 
 assert(!(is_debug && is_official_build), "Can't do official debug builds")
 assert(!(current_os == "ios" && is_component_build),
        "Can't use component build on iOS")
-assert(!(current_os == "tvos" && is_component_build),
-       "Can't use component build on tvOS")
 assert(!(current_os == "watchos" && is_component_build),
        "Can't use component build on watchOS")
 
@@ -317,11 +315,10 @@ is_ios = current_os == "ios"
 is_linux = current_os == "linux"
 is_mac = current_os == "mac"
 is_nacl = current_os == "nacl"
-is_tvos = current_os == "tvos"
 is_watchos = current_os == "watchos"
 is_win = current_os == "win" || current_os == "winuwp"
 
-is_apple = is_ios || is_mac || is_tvos || is_watchos
+is_apple = is_ios || is_mac || is_watchos
 is_posix = !is_win && !is_fuchsia
 
 # =============================================================================

build/config/apple/mobile_config.gni

@@ -2,11 +2,19 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+import("//build/config/features.gni")  # For `use_blink`
+
 declare_args() {
   # Configure the environment for which to build. Could be either "device",
   # "simulator" or "catalyst". Must be specified.
   target_environment = ""
 
+  # Valid values: "iphoneos" (default), "tvos", "watchos".
+  # Indicates the kind of iOS or iOS-based platform that is being targeted.
+  # Note that this value is available only when is_ios is also true (i.e. it
+  # cannot be used with the host toolchain).
+  target_platform = "iphoneos"
+
   # Control whether codesiging is enabled (ignored for simulator builds).
   # TODO(crbug.com/378918882): Prefix with apple_mobile_ instead of ios_.
   ios_enable_code_signing = true
@@ -60,12 +68,28 @@ shared_bundle_id_for_test_apps =
 # the variables can only be executed if building for ios or watchos (as they
 # either have no meaning or depend on tools that are only available on macOS).
 if (is_ios || is_watchos) {
-  # Check that target_environment is set to a supported value.
+  # Check that target_platform and target_environment are set to supported
+  # values.
+  _target_platforms = []
+  if (is_ios) {
+    _target_platforms += [
+      "iphoneos",
+      "tvos",
+    ]
+  } else if (is_watchos) {
+    _target_platforms += [
+      "iphoneos",
+      "watchos",
+    ]
+  }
+  assert(filter_include([ target_platform ], _target_platforms) != [],
+         "target_platform '$target_platform' does not match a target value: " +
+             "$_target_platforms")
   _target_environments = [
     "simulator",
     "device",
   ]
-  if (is_ios) {
+  if (is_ios && target_platform == "iphoneos") {
     _target_environments += [ "catalyst" ]
   }
   assert(filter_include([ target_environment ], _target_environments) != [],
@@ -99,4 +123,13 @@ if (is_ios || is_watchos) {
                       "trim string")
     }
   }
+
+  # Sanity check: tvOS builds require `use_blink`.
+  if (target_platform == "tvos") {
+    assert(use_blink, "tvOS builds require use_blink=true")
+  }
+} else {
+  # On host toolchains, checking this value does not make sense. Set it to
+  # something invalid to prevent checks for specific values from passing.
+  target_platform = ""
 }

content/app/content_main.cc

@@ -310,13 +310,12 @@ NO_STACK_PROTECTOR int RunContentProcess(
     base::CommandLine* command_line = base::CommandLine::ForCurrentProcess();
     command_line->AppendSwitch(switches::kEnableViewport);
     command_line->AppendSwitch(embedder_support::kUseMobileUserAgent);
-#endif
 
-#if BUILDFLAG(IS_TVOS)
+#if BUILDFLAG(IS_IOS_TVOS)
     // Set tvOS to single-process mode by default.
-    base::CommandLine* command_line = base::CommandLine::ForCurrentProcess();
     command_line->AppendSwitch(switches::kSingleProcess);
 #endif
+#endif
 
 #if (BUILDFLAG(IS_CHROMEOS) || BUILDFLAG(IS_LINUX)) && !defined(COMPONENT_BUILD)
     base::subtle::EnableFDOwnershipEnforcement(true);

content/browser/BUILD.gn

@@ -49,6 +49,10 @@ if (is_android) {
   }
 }
 
+if (is_ios) {
+  import("//build/config/apple/mobile_config.gni")  # For `target_platform`
+}
+
 source_set("browser") {
   # Only the public target should depend on this. All other targets (even
   # internal content ones) should depend on the public one.
@@ -2812,7 +2816,7 @@ source_set("browser") {
       "IOSurface.framework",
       "UniformTypeIdentifiers.framework",
     ]
-  } else if (is_ios || is_tvos) {
+  } else if (is_ios) {
     sources += [
       "date_time_chooser/ios/date_time_chooser_coordinator.h",
       "date_time_chooser/ios/date_time_chooser_coordinator.mm",
@@ -2847,11 +2851,11 @@ source_set("browser") {
       "web_contents/web_contents_view_ios.mm",
     ]
 
-    if (is_tvos) {
-      sources += [ "child_process_launcher_helper_tvos.mm" ]
-    } else {
+    if (target_platform != "tvos") {
       sources += [ "child_process_launcher_helper_ios.mm" ]
       frameworks += [ "BrowserEngineKit.framework" ]
+    } else {
+      sources += [ "child_process_launcher_helper_tvos.mm" ]
     }
 
     frameworks += [ "IOSurface.framework" ]

content/browser/child_process_launcher_helper_tvos.mm

@@ -7,9 +7,6 @@
 #include "content/browser/child_process_launcher_helper.h"
 #include "content/browser/child_process_launcher_helper_posix.h"
 
-static_assert(BUILDFLAG(IS_TVOS),
-              "child_process_launcher_helper_tvos.mm requires is_tvos");
-
 // TODO(crbug.com/391914246): Implement the ChildProcessLauncherHelper when
 // tvOS actually requires the functionality.
 namespace content {

media/midi/BUILD.gn

@@ -15,6 +15,10 @@ if (is_android) {
   import("//third_party/jni_zero/jni_zero.gni")
 }
 
+if (is_ios) {
+  import("//build/config/apple/mobile_config.gni")  # For `target_platform`
+}
+
 # Common configuration for targets in the media/midi directory.
 config("midi_config") {
   if (use_alsa && use_udev) {
@@ -128,7 +132,9 @@ component("midi") {
   }
 
   if (is_apple) {
-    if (!is_tvos) {
+    if (is_ios && target_platform == "tvos") {
+      sources += [ "midi_manager_tvos.cc" ]
+    } else {
       sources += [
         "midi_manager_mac.cc",
         "midi_manager_mac.h",
@@ -138,8 +144,6 @@ component("midi") {
         "CoreFoundation.framework",
         "CoreMIDI.framework",
       ]
-    } else {
-      sources += [ "midi_manager_tvos.cc" ]
     }
   }
 

media/midi/midi_manager_tvos.cc

@@ -6,8 +6,6 @@
 #include "media/midi/midi_manager.h"
 #include "media/midi/midi_service.h"
 
-static_assert(BUILDFLAG(IS_TVOS), "midi_manager_tvos.cc requires is_tvos");
-
 namespace midi {
 
 MidiManager* MidiManager::Create(MidiService* service) {

ui/base/clipboard/BUILD.gn

@@ -7,6 +7,10 @@ import("//build/config/features.gni")
 import("//build/config/ui.gni")
 import("//testing/libfuzzer/fuzzer_test.gni")
 
+if (is_ios) {
+  import("//build/config/apple/mobile_config.gni")  # For `target_platform`
+}
+
 component("clipboard_types") {
   output_name = "ui_base_clipboard_types"
   sources = [
@@ -128,14 +132,14 @@ component("clipboard") {
   }
 
   if (is_ios) {
-    sources += [
-      "clipboard_ios.h",
-      "clipboard_ios.mm",
-    ]
-  }
-
-  if (is_tvos) {
-    sources += [ "clipboard_tvos.mm" ]
+    if (target_platform == "tvos") {
+      sources += [ "clipboard_tvos.mm" ]
+    } else {
+      sources += [
+        "clipboard_ios.h",
+        "clipboard_ios.mm",
+      ]
+    }
   }
 
   if (is_win) {