Set use_accelerated_compositing gyp variable to 1 whenever the gpu compositor...

build/features_override.gypi

 # Copyright (c) 2009 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.
 
 # This file is only included in full-chromium builds, and overrides the
 # feature_defines variable in third_party/WebKit/WebKit/chromium/features.gypi.
 {
   'variables': {
     # WARNING: This list of strings completely replaces the list in
     # features.gypi. Therefore, if an enable is listed in features.gypi
@@ skipping 44 matching lines @@
     },
     'use_accelerated_compositing%': '<(use_accelerated_compositing)',
     'enable_svg%': '<(enable_svg)',
     'enable_touch_events%': '<(enable_touch_events)',
     'conditions': [
       ['OS=="win" or use_accelerated_compositing==1', {
         'feature_defines': [
          'WTF_USE_ACCELERATED_COMPOSITING=1',
          'ENABLE_3D_RENDERING=1',
         ],
+        'use_accelerated_compositing': 1,
       }],
     ],
     # TODO: If the need arises, create a mechanism that will intelligently
     # merge the lists rather than replace one with the other. This may
     # require changes in gyp.
   },
 
 }
 
 # Local Variables:
 # tab-width:2
 # indent-tabs-mode:nil
 # End:
 # vim: set expandtab tabstop=2 shiftwidth=2: