cc: Make PrepareToDraw return an enum for why it aborts

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,
   },
   'targets': [
     {
@@ skipping 387 matching lines @@
         'resources/transferable_resource.h',
         'resources/ui_resource_bitmap.cc',
         'resources/ui_resource_bitmap.h',
         'resources/ui_resource_client.h',
         'resources/ui_resource_request.cc',
         'resources/ui_resource_request.h',
         'resources/video_resource_updater.cc',
         'resources/video_resource_updater.h',
         'scheduler/delay_based_time_source.cc',
         'scheduler/delay_based_time_source.h',
+        'scheduler/draw_swap_readback_result.h',
         'scheduler/frame_rate_controller.cc',
         'scheduler/frame_rate_controller.h',
         'scheduler/rolling_time_delta_history.cc',
         'scheduler/rolling_time_delta_history.h',
         'scheduler/scheduler.cc',
         'scheduler/scheduler.h',
         'scheduler/scheduler_settings.cc',
         'scheduler/scheduler_settings.h',
         'scheduler/scheduler_state_machine.cc',
         'scheduler/scheduler_state_machine.h',
@@ skipping 49 matching lines @@
       'sources': [
         'surfaces/surface.cc',
         'surfaces/surface.h',
         'surfaces/surface_manager.cc',
         'surfaces/surface_manager.h',
         'surfaces/surfaces_export.h',
       ],
     },
   ],
 }