Implement the Platform::sharedOffscreenGraphicsContext3D method.

webkit/gpu/webkit_gpu.gypi

 # 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': {
     'conditions': [
       ['inside_chromium_build==0', {
         'webkit_src_dir': '../../../../..',
       },{
@@ skipping 15 matching lines @@
         '<(DEPTH)/gpu/gpu.gyp:gles2_c_lib',
         '<(DEPTH)/gpu/gpu.gyp:gles2_implementation',
         '<(DEPTH)/skia/skia.gyp:skia',
         '<(DEPTH)/third_party/angle/src/build_angle.gyp:translator_glsl',
         '<(DEPTH)/ui/gl/gl.gyp:gl',
         '<(DEPTH)/ui/ui.gyp:ui',
         '<(webkit_src_dir)/Source/WebKit/chromium/WebKit.gyp:webkit',
       ],
       'sources': [
         # This list contains all .h and .cc in gpu except for test code.
+        'context_provider_in_process.cc',
+        'context_provider_in_process.h',
         'gl_bindings_skia_cmd_buffer.cc',
         'gl_bindings_skia_cmd_buffer.h',
         'grcontext_for_webgraphicscontext3d.cc',
         'grcontext_for_webgraphicscontext3d.h',
+        'test_context_provider_factory.cc',
+        'test_context_provider_factory.h',
         'webgraphicscontext3d_in_process_command_buffer_impl.cc',
         'webgraphicscontext3d_in_process_command_buffer_impl.h',
         'webgraphicscontext3d_in_process_impl.cc',
         'webgraphicscontext3d_in_process_impl.h',
         'webkit_gpu.gypi',
       ],
       'conditions': [
         ['inside_chromium_build==0', {
           'dependencies': [
             '<(DEPTH)/webkit/support/setup_third_party.gyp:third_party_headers',
           ],
         }],
       ],
       'defines': [
         'WEBKIT_GPU_IMPLEMENTATION',
       ],
       # TODO(jschuh): crbug.com/167187 fix size_t to int truncations.
       'msvs_disabled_warnings': [ 4267, ],
     },
   ],
 }