Use gpu::Mailbox in IPCs instead of std::string

ui/compositor/compositor.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': [
     {
       'target_name': 'compositor',
       'type': '<(component)',
       'dependencies': [
         '<(DEPTH)/base/base.gyp:base',
         '<(DEPTH)/base/third_party/dynamic_annotations/dynamic_annotations.gyp:dynamic_annotations',
         '<(DEPTH)/cc/cc.gyp:cc',
+        '<(DEPTH)/gpu/gpu.gyp:gpu',
         '<(DEPTH)/skia/skia.gyp:skia',
         '<(DEPTH)/third_party/WebKit/Source/WebKit/chromium/WebKit.gyp:webkit',
         '<(DEPTH)/ui/gl/gl.gyp:gl',
         '<(DEPTH)/ui/ui.gyp:ui',
         '<(DEPTH)/webkit/gpu/webkit_gpu.gyp:webkit_gpu',
       ],
       'defines': [
         'COMPOSITOR_IMPLEMENTATION',
       ],
       'sources': [
@@ skipping 112 matching lines @@
         # osmesa GL implementation is used on linux.
         ['OS=="linux"', {
           'dependencies': [
             '<(DEPTH)/third_party/mesa/mesa.gyp:osmesa',
           ],
         }],
       ],
     },
   ],
 }