Add Protobuf support for cc/playback skia usage

cc/cc_tests.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_unit_tests_source_files': [
       'animation/animation_host_unittest.cc',
       'animation/animation_player_unittest.cc',
@@ skipping 67 matching lines @@
       'output/renderer_pixeltest.cc',
       'output/renderer_unittest.cc',
       'output/shader_unittest.cc',
       'output/software_renderer_unittest.cc',
       'output/texture_mailbox_deleter_unittest.cc',
       'playback/discardable_image_map_unittest.cc',
       'playback/display_item_list_unittest.cc',
       'playback/display_list_raster_source_unittest.cc',
       'playback/display_list_recording_source_unittest.cc',
       'proto/gfx_conversions_unittest.cc',
+      'proto/skia_conversions_unittest.cc',
       'quads/draw_polygon_unittest.cc',
       'quads/draw_quad_unittest.cc',
       'quads/render_pass_unittest.cc',
       'raster/scoped_gpu_raster_unittest.cc',
       'raster/task_graph_runner_unittest.cc',
       'raster/texture_compressor_etc1_unittest.cc',
       'raster/tile_task_worker_pool_unittest.cc',
       'resources/platform_color_unittest.cc',
       'resources/resource_pool_unittest.cc',
       'resources/resource_provider_unittest.cc',
@@ skipping 362 matching lines @@
                   '../tools/xdisplaycheck/xdisplaycheck.gyp:xdisplaycheck',
                 ],
               }
             ],
           ],
         },
       ],
     }],
   ],
 }