Use a struct for cc::Surface ids for more type safety

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 476 matching lines @@
       ],
       'defines': [
         'CC_SURFACES_IMPLEMENTATION=1',
       ],
       'sources': [
         'surfaces/display.cc',
         'surfaces/display.h',
         'surfaces/display_client.h',
         'surfaces/surface.cc',
         'surfaces/surface.h',
+        'surfaces/surface_id.h',
         'surfaces/surface_aggregator.cc',
         'surfaces/surface_aggregator.h',
         'surfaces/surface_client.h',
         'surfaces/surface_manager.cc',
         'surfaces/surface_manager.h',
         'surfaces/surfaces_export.h',
       ],
     },
   ],
 }