Add a GN option to use Chromium style naming with the Blink GC plugin.

third_party/WebKit/Source/BUILD.gn

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("config.gni")
 if (is_clang) {
   import("//build/config/clang/clang.gni")
 }
 
 visibility = [ "//third_party/WebKit/*" ]
 
 # arguments --------------------------------------------------------------------
 
 declare_args() {
   # Set to true to enable the clang plugin that checks the usage of the  Blink
   # garbage-collection infrastructure during compilation.
   blink_gc_plugin = true
 
   # Set to true to have the clang Blink GC plugin emit class graph (in JSON)
   # with typed pointer edges; for debugging or other (internal) uses.
   blink_gc_plugin_option_do_dump_graph = false
 
   # Set to true to have the clang Blink GC plugin additionally check if
   # a class has an empty destructor which would be unnecessarily invoked
   # when finalized.
   blink_gc_plugin_option_warn_unneeded_finalizer = false
+
+  # Set to true to have the clang Blink GC plugin use Chromium-style naming
+  # rather than legacy Blink name.
+  # TODO(https://crbug.com/675879): Remove this option after the Blink rename.
+  blink_gc_plugin_option_use_chromium_style_naming = false
 }
 
 # features ---------------------------------------------------------------------
 
 config("features") {
   defines = feature_defines_list
 }
 
 # inside_blink -----------------------------------------------------------------
 
@@ skipping 105 matching lines @@
       ]
     }
     if (blink_gc_plugin_option_warn_unneeded_finalizer) {
       cflags += [
         "-Xclang",
         "-plugin-arg-blink-gc-plugin",
         "-Xclang",
         "warn-unneeded-finalizer",
       ]
     }
+    if (blink_gc_plugin_option_use_chromium_style_naming) {
+      cflags += [
+        "-Xclang",
+        "-plugin-arg-blink-gc-plugin",
+        "-Xclang",
+        "use-chromium-style-naming",
+      ]
+    }
   }
 }
 
 # The follow configs apply to all targets except for unit tests, which rely on
 # static initializers.
 config("non_test_config") {
   cflags = []
 
   if (is_clang) {
     cflags += [ "-Wglobal-constructors" ]
   }
 }
 
 if (is_mac) {
   # This sets up precompiled headers for Mac.
   config("mac_precompiled_headers") {
     precompiled_header = rebase_path("build/mac/Prefix.h", root_build_dir)
     precompiled_source = "//third_party/WebKit/Source/build/mac/Prefix.h"
   }
 }