cc: Add CopyAsBitmapRequest class to hold the readback callback.

cc/cc.gyp

 # 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.
 
 {
   'variables': {
     'chromium_code': 1,
     'cc_source_files': [
       'animation/animation.cc',
       'animation/animation.h',
@@ skipping 146 matching lines @@
       'layers/video_layer.h',
       'layers/video_layer_impl.cc',
       'layers/video_layer_impl.h',
       'output/compositor_frame.cc',
       'output/compositor_frame.h',
       'output/compositor_frame_ack.cc',
       'output/compositor_frame_ack.h',
       'output/compositor_frame_metadata.cc',
       'output/compositor_frame_metadata.h',
       'output/context_provider.h',
+      'output/copy_output_request.cc',
+      'output/copy_output_request.h',
       'output/delegated_frame_data.h',
       'output/delegated_frame_data.cc',
       'output/delegating_renderer.cc',
       'output/delegating_renderer.h',
       'output/direct_renderer.cc',
       'output/direct_renderer.h',
       'output/geometry_binding.cc',
       'output/geometry_binding.h',
       'output/gl_frame_data.h',
       'output/gl_frame_data.cc',
@@ skipping 187 matching lines @@
         'CC_IMPLEMENTATION=1',
       ],
       'sources': [
         '<@(cc_source_files)',
       ],
       # TODO(jschuh): crbug.com/167187 fix size_t to int truncations.
       'msvs_disabled_warnings': [ 4267, ],
     },
   ],
 }