gpu: Add YCbCr 420v extension.

gpu/command_buffer/build_gles2_cmd_buffer.py

 #!/usr/bin/env 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.
 
 """code generator for GLES2 command buffers."""
 
 import itertools
 import os
 import os.path
@@ skipping 1879 matching lines @@
       'GL_LUMINANCE32F_EXT',
       'GL_LUMINANCE_ALPHA32F_EXT',
     ],
   },
   'ImageInternalFormat': {
     'type': 'GLenum',
     'valid': [
       'GL_RGB',
       'GL_RGB_YUV_420_CHROMIUM',
       'GL_RGB_YCBCR_422_CHROMIUM',
+      'GL_RGB_YCBCR_420V_CHROMIUM',
       'GL_RGBA',
     ],
   },
   'ImageUsage': {
     'type': 'GLenum',
     'valid': [
       'GL_READ_WRITE_CHROMIUM',
     ],
   },
   'ValueBufferTarget': {
@@ skipping 9202 matching lines @@
   Format(gen.generated_cpp_filenames)
 
   if gen.errors > 0:
     print "%d errors" % gen.errors
     return 1
   return 0
 
 
 if __name__ == '__main__':
   sys.exit(main(sys.argv[1:]))