Implement Discard and EnsureBackbufferCHROMIUM using command buffer instead of IPC.

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 os
 import os.path
 import sys
@@ skipping 1621 matching lines @@
     'client_test': False,
     'gl_test_func': 'glGetQueryiv',
     'pepper_interface': 'Query',
   },
   'GetQueryObjectuivEXT': {
     'gen_cmd': False,
     'client_test': False,
     'gl_test_func': 'glGetQueryObjectuiv',
     'pepper_interface': 'Query',
   },
+  'DiscardBackbufferCHROMIUM': {
+      'type': 'Custom',
+      'impl_func': False,
+      'unit_test': False,
+      'extension': True,
+      'chromium': True,
+  },
+  'EnsureBackbufferCHROMIUM': {
+      'type': 'Custom',
+      'impl_func': False,
+      'unit_test': False,
+      'extension': True,
+      'chromium': True,
+  },
 }
 
 
 def SplitWords(input_string):
   """Transforms a input_string into a list of lower-case components.
 
   Args:
     input_string: the input string.
 
   Returns:
@@ skipping 4553 matching lines @@
     gen.WriteCommonUtilsImpl("common/gles2_cmd_utils_implementation_autogen.h")
 
   if gen.errors > 0:
     print "%d errors" % gen.errors
     return 1
   return 0
 
 
 if __name__ == '__main__':
   sys.exit(main(sys.argv[1:]))