Add support for use_blink gn variable to conditionally compile blink.

Blink (and the relevant support code, content, components) was
conditionally compiled based on is_ios. Clean this up so it is compiled
based on a top level GN variable.

Bug: 1411704
Change-Id: Ib7dbb1f6d4edf4acf40ce77875a811762ec8cd26
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4207057
Reviewed-by: Rohit Rao <rohitrao@chromium.org>
Reviewed-by: John Abd-El-Malek <jam@chromium.org>
Commit-Queue: Dave Tapuska <dtapuska@chromium.org>
Reviewed-by: Avi Drissman <avi@chromium.org>
Reviewed-by: Dirk Pranke <dpranke@google.com>
Cr-Commit-Position: refs/heads/main@{#1100099}

build/BUILD.gn

@@ -7,6 +7,7 @@ import("//build/config/chrome_build.gni")
 import("//build/config/chromecast_build.gni")
 import("//build/config/chromeos/args.gni")
 import("//build/config/chromeos/ui_mode.gni")
+import("//build/config/features.gni")
 import("//build/util/process_version.gni")
 import("//build_overrides/build.gni")
 
@@ -30,6 +31,11 @@ buildflag_header("branding_buildflags") {
   }
 }
 
+buildflag_header("blink_buildflags") {
+  header = "blink_buildflags.h"
+  flags = [ "USE_BLINK=$use_blink" ]
+}
+
 buildflag_header("chromecast_buildflags") {
   header = "chromecast_buildflags.h"
 

build/config/features.gni

@@ -36,6 +36,8 @@ declare_args() {
   use_dbus = is_linux || is_chromeos
 
   use_gio = is_linux && !is_castos
+
+  use_blink = !is_ios
 }
 #
 # =============================================

chrome/common/features.gni

@@ -23,7 +23,7 @@ import("//printing/buildflags/buildflags.gni")
 import("//ui/base/ui_features.gni")
 import("//ui/webui/webui_features.gni")
 
-assert(!is_ios, "Chromium/iOS shouldn't use anything in //chrome")
+assert(use_blink, "Chromium without blink shouldn't use anything in //chrome")
 
 # Please keep features in alphabetical order.
 declare_args() {

content/BUILD.gn

@@ -2,6 +2,7 @@
 # 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")
 import("//build/config/nacl/config.gni")
 import("//ppapi/buildflags/buildflags.gni")
 import("//tools/grit/grit_rule.gni")
@@ -12,7 +13,7 @@ config("content_implementation") {
   configs = [ "//build/config/compiler:wexit_time_destructors" ]
 }
 
-assert(!is_ios, "Chromium/iOS shouldn't use anything in //content")
+assert(use_blink, "Chromium without blink shouldn't use anything in //content")
 
 # When targets depend on, e.g. //content/public/browser, what happens? To
 # facilitate the complexity here, the "public" targets are groups that forward

ios/build/config.gni

@@ -2,6 +2,8 @@
 # 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")
+
 # Global list of dependencies that are conceptually bad on iOS and should
 # never be added (they will never be supported).
 _ios_conceptually_bad_dependencies = [
@@ -28,5 +30,7 @@ ios_extension_assert_no_deps = [
   "//url/*",
 ]
 
-ios_assert_no_deps =
-    _ios_conceptually_bad_dependencies + _ios_transient_bad_dependencies
+ios_assert_no_deps = _ios_transient_bad_dependencies
+if (!use_blink) {
+  ios_assert_no_deps += _ios_conceptually_bad_dependencies
+}

ios/build/tools/setup-gn.config

@@ -38,3 +38,4 @@ filter_a = "//ui/base:ui_base_unittests"
 filter_b = "//ui/gfx:gfx_unittests"
 filter_c = "//url:url_unittests"
 filter_d = "//third_party/crashpad/*"
+filter_e = "//content/shell/*"

third_party/BUILD.gn

@@ -2,11 +2,14 @@
 # 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")
 import("//build/config/freetype/freetype.gni")
 import("//third_party/harfbuzz-ng/harfbuzz.gni")
 import("//third_party/libjpeg.gni")
 
-assert(!is_ios, "This is not used on iOS, don't drag it in unintentionally")
+assert(
+    use_blink,
+    "This is not used on if blink is not enabled, don't drag it in unintentionally")
 
 config("system_libjpeg_config") {
   libs = [ "jpeg" ]

third_party/blink/renderer/platform/wtf/BUILD.gn

@@ -2,7 +2,9 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-assert(!is_ios)
+import("//build/config/features.gni")
+
+assert(use_blink)
 
 import("//build/buildflag_header.gni")
 import("//build/config/compiler/compiler.gni")