Implement EXT_draw_buffers WebGL extention support in command buffer.

ui/gl/generate_bindings.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 GL/GLES extension wrangler."""
 
 import optparse
 import os
 import collections
@@ skipping 171 matching lines @@
 { 'return_type': 'void',
   'names': ['glDisableVertexAttribArray'],
   'arguments': 'GLuint index', },
 { 'return_type': 'void',
   'names': ['glDrawArrays'],
   'arguments': 'GLenum mode, GLint first, GLsizei count', },
 { 'return_type': 'void',
   'names': ['glDrawBuffer'],
   'arguments': 'GLenum mode', },
 { 'return_type': 'void',
-  'names': ['glDrawBuffersARB'],
+  'names': ['glDrawBuffersARB', 'glDrawBuffersEXT'],
   'arguments': 'GLsizei n, const GLenum* bufs', },
 { 'return_type': 'void',
   'names': ['glDrawElements'],
   'arguments':
       'GLenum mode, GLsizei count, GLenum type, const void* indices', },
 { 'return_type': 'void',
   'names': ['glEGLImageTargetTexture2DOES'],
   'arguments': 'GLenum target, GLeglImageOES image', },
 { 'return_type': 'void',
   'names': ['glEGLImageTargetRenderbufferStorageOES'],
@@ skipping 1616 matching lines @@
     header_file.close()
 
   source_file = open(os.path.join(dir, 'gl_bindings_autogen_mock.cc'), 'wb')
   GenerateMockSource(source_file, GL_FUNCTIONS)
   source_file.close()
   return 0
 
 
 if __name__ == '__main__':
   sys.exit(main(sys.argv[1:]))