Ozone: Dont hardcode format to YUV when using Overlay Composition.

ui/ozone/platform/drm/gbm.gypi

 # Copyright 2014 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': {
     'internal_ozone_platform_deps': [
       'ozone_platform_gbm',
     ],
     'internal_ozone_platform_unittest_deps': [
@@ skipping 50 matching lines @@
         'gpu/drm_device_generator.cc',
         'gpu/drm_device_generator.h',
         'gpu/drm_device_manager.cc',
         'gpu/drm_device_manager.h',
         'gpu/drm_display.cc',
         'gpu/drm_display.h',
         'gpu/drm_gpu_display_manager.cc',
         'gpu/drm_gpu_display_manager.h',
         'gpu/drm_gpu_platform_support.cc',
         'gpu/drm_gpu_platform_support.h',
+        'gpu/drm_overlay_candidate.cc',
+        'gpu/drm_overlay_candidate.h',
         'gpu/drm_thread.cc',
         'gpu/drm_thread.h',
         'gpu/drm_thread_message_proxy.cc',
         'gpu/drm_thread_message_proxy.h',
         'gpu/drm_thread_proxy.cc',
         'gpu/drm_thread_proxy.h',
         'gpu/drm_vsync_provider.cc',
         'gpu/drm_vsync_provider.h',
         'gpu/drm_window.cc',
         'gpu/drm_window.h',
@@ skipping 95 matching lines @@
           'gpu/mock_buffer_generator.cc',
           'gpu/mock_buffer_generator.h',
           'gpu/mock_drm_device.cc',
           'gpu/mock_drm_device.h',
           'gpu/screen_manager_unittest.cc',
         ],
       },
     },
   ],
 }