Add support for GL_CHROMIUM_pixel_transfer_buffer_object.

ppapi/native_client/src/shared/ppapi_proxy/nacl.scons

 # -*- python -*-
 # 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.
 
 Import('env')
 
 # Underlay $SOURCE_ROOT/gpu in this directory.
 Dir('.').addRepository(Dir('#/../gpu'))
 
 # To enable getting the generated include files and sources and also common and
 # client GPU command buffer sources.
 env.Append(CPPPATH=
           ['${SOURCE_ROOT}/native_client/src/shared/ppapi_proxy/untrusted',
            '$SOURCE_ROOT/third_party/khronos', '$SOURCE_ROOT/gpu'])
 
 env.Append(CPPDEFINES=['XP_UNIX'])
 env.FilterOut(CCFLAGS=['-Wswitch-enum'])
 env.Append(CCFLAGS=['-Wno-long-long'])
 
 command_buffer_common_srcs = [
     'command_buffer/common/cmd_buffer_common.cc',
     'command_buffer/common/gles2_cmd_format.cc',
     'command_buffer/common/gles2_cmd_utils.cc',
     'command_buffer/common/logging.cc',
     ]
 
 command_buffer_client_srcs = [
     'command_buffer/client/atomicops.cc',
+    'command_buffer/client/buffer_tracker.cc',
     'command_buffer/client/cmd_buffer_helper.cc',
     'command_buffer/client/fenced_allocator.cc',
     'command_buffer/client/gles2_c_lib.cc',
     'command_buffer/client/gles2_cmd_helper.cc',
     'command_buffer/client/gles2_implementation.cc',
     'command_buffer/client/program_info_manager.cc',
     'command_buffer/client/gles2_lib.cc',
     'command_buffer/client/mapped_memory.cc',
     'command_buffer/client/query_tracker.cc',
     'command_buffer/client/ring_buffer.cc',
@@ skipping 80 matching lines @@
          'srpc',
          'gio',
          'platform',
         ])
 
 header_install = env.AddHeaderToSdk(['ppruntime.h'])
 env.AddLibraryToSdk(libppruntime)
 
 # Clients that overload main() will use ppruntime.h.
 env.Requires(libppruntime, header_install)