implement getBufferSubDataAsync prototype

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 2991 matching lines @@
     'result': ['SizedResult<GLuint>'],
   },
   'GetAttribLocation': {
     'type': 'Custom',
     'data_transfer_methods': ['shm'],
     'cmd_args':
         'GLidProgram program, uint32_t name_bucket_id, GLint* location',
     'result': ['GLint'],
     'error_return': -1,
   },
+  'GetBufferSubDataAsyncCHROMIUM': {
+    'type': 'Custom',
+    'data_transfer_methods': ['shm'],
+    'cmd_args': 'GLenumBufferTarget target, GLintptrNotNegative offset, '
+                'GLsizeiptr size, '
+                'uint32_t data_shm_id, uint32_t data_shm_offset',
+    'unsafe': True,
+    'impl_func': False,
+    'client_test': False,
+    'trace_level': 1,
+  },
   'GetFragDataIndexEXT': {
     'type': 'Custom',
     'data_transfer_methods': ['shm'],
     'cmd_args':
         'GLidProgram program, uint32_t name_bucket_id, GLint* index',
     'result': ['GLint'],
     'error_return': -1,
     'extension': 'EXT_blend_func_extended',
     'extension_flag': 'ext_blend_func_extended',
   },
@@ skipping 8313 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:]))