Switch ChromeOS and ChromeCast to use external V8 snapshot files.

build/common.gypi

 # Copyright (c) 2012 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.
 
 # IMPORTANT:
 # Please don't directly include this file if you are building via gyp_chromium,
 # since gyp_chromium is automatically forcing its inclusion.
 {
   # Variables expected to be overriden on the GYP command line (-D) or by
   # ~/.gyp/include.gypi.
@@ skipping 1004 matching lines @@
           'sas_dll_path%': '<(DEPTH)/third_party/platformsdk_win7/files/redist/x86',
         }],
 
         # Turn on JNI generation optimizations on non-WebView builds.
         ['OS=="android" and android_webview_build==0', {
           'optimize_jni_generation%': 1,
         }, {
           'optimize_jni_generation%': 0,
         }],
 
-        # TODO(rmcilroy): Enable v8_use_external_startup_data on ChromeOS
-        # http://crbug.com/421063
-        ['chromecast==0 and chromeos==0 and OS!="ios"', {
+        # TODO(rmcilroy): Remove ios check. http://crbug.com/421063.
+        ['OS!="ios"', {
           'v8_use_external_startup_data%': 1,
         }, {
           'v8_use_external_startup_data%': 0,
         }],
       ],
 
       # Set this to 1 to enable use of concatenated impulse responses
       # for the HRTF panner in WebAudio.
       'use_concatenated_impulse_responses': 1,
 
@@ skipping 5063 matching lines @@
     # settings in target dicts.  SYMROOT is a special case, because many other
     # Xcode variables depend on it, including variables such as
     # PROJECT_DERIVED_FILE_DIR.  When a source group corresponding to something
     # like PROJECT_DERIVED_FILE_DIR is added to a project, in order for the
     # files to appear (when present) in the UI as actual files and not red
     # red "missing file" proxies, the correct path to PROJECT_DERIVED_FILE_DIR,
     # and therefore SYMROOT, needs to be set at the project level.
     'SYMROOT': '<(DEPTH)/xcodebuild',
   },
 }