Add support for GL_CHROMIUM_pixel_transfer_buffer_object.

ppapi/native_client/src/shared/ppapi_proxy/ppapi_proxy_untrusted.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.
 
 {
   'includes': [
     '../../../../../native_client/build/common.gypi',
   ],
   'targets': [
     {
@@ skipping 14 matching lines @@
           '<(DEPTH)/ppapi/native_client/src/shared/ppapi_proxy/untrusted',
         ],
         'sources': [
           '<(DEPTH)/gpu/command_buffer/common/cmd_buffer_common.cc',
           '<(DEPTH)/gpu/command_buffer/common/debug_marker_manager.cc',
           '<(DEPTH)/gpu/command_buffer/common/gles2_cmd_format.cc',
           '<(DEPTH)/gpu/command_buffer/common/gles2_cmd_utils.cc',
           '<(DEPTH)/gpu/command_buffer/common/logging.cc',
 
           '<(DEPTH)/gpu/command_buffer/client/atomicops.cc',
+          '<(DEPTH)/gpu/command_buffer/client/buffer_tracker.cc',
           '<(DEPTH)/gpu/command_buffer/client/client_context_state.cc',
           '<(DEPTH)/gpu/command_buffer/client/cmd_buffer_helper.cc',
           '<(DEPTH)/gpu/command_buffer/client/fenced_allocator.cc',
           '<(DEPTH)/gpu/command_buffer/client/gles2_c_lib.cc',
           '<(DEPTH)/gpu/command_buffer/client/gles2_cmd_helper.cc',
           '<(DEPTH)/gpu/command_buffer/client/gles2_implementation.cc',
           '<(DEPTH)/gpu/command_buffer/client/gles2_interface.cc',
           '<(DEPTH)/gpu/command_buffer/client/program_info_manager.cc',
           '<(DEPTH)/gpu/command_buffer/client/transfer_buffer.cc',
           '<(DEPTH)/gpu/command_buffer/client/gles2_lib.cc',
@@ skipping 66 matching lines @@
           'view_data.cc',
           # Autogenerated files
           'ppp_rpc_server.cc',
           'ppb_rpc_client.cc',
           'upcall_client.cc'
         ],
       },
     },
   ],
 }