Turns on use_mojo=1 for windows.

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 818 matching lines @@
         }],
 
         # By default, use ICU data file (icudtl.dat) on all platforms
         # except when building Android WebView.
         # TODO(jshin): Handle 'use_system_icu' on Linux (Chromium).
         ['android_webview_build==0', {
           'icu_use_data_file_flag%' : 1,
         }, {
           'icu_use_data_file_flag%' : 0,
         }],
+
+        ['OS=="win"', {
+          'use_mojo%': 1,
+        }],
       ],
 
       # Set this to 1 to enable use of concatenated impulse responses
       # for the HRTF panner in WebAudio.
       'use_concatenated_impulse_responses': 1,
 
       # You can set the variable 'use_official_google_api_keys' to 1
       # to use the Google-internal file containing official API keys
       # for Google Chrome even in a developer build.  Setting this
       # variable explicitly to 1 will cause your build to fail if the
@@ skipping 4254 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',
   },
 }