Use enum string instead of value in code generator.

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 1354 matching lines @@
     'valid': [
       'GL_GUILTY_CONTEXT_RESET_ARB',
       'GL_INNOCENT_CONTEXT_RESET_ARB',
       'GL_UNKNOWN_CONTEXT_RESET_ARB',
     ],
   },
   'SyncCondition': {
     'type': 'GLenum',
     'is_complete': True,
     'valid': [
-      #TODO(zmo): avoid using the direct number.
-      '0x9117',  # GL_SYNC_GPU_COMMANDS_COMPLETE
+      'GL_SYNC_GPU_COMMANDS_COMPLETE',
     ],
     'invalid': [
       '0',
     ],
   },
   'SyncFlags': {
     'type': 'GLbitfield',
     'is_complete': True,
     'valid': [
       '0',
@@ skipping 7495 matching lines @@
     file.Write("#undef GLES2_CMD_OP\n")
     file.Write("  kNumCommands\n")
     file.Write("};\n")
     file.Write("\n")
     file.Close()
     self.generated_cpp_filenames.append(file.filename)
 
   def WriteFormat(self, filename):
     """Writes the command buffer format"""
     file = CHeaderWriter(filename)
+    # Forward declaration of a few enums used in constant argument
+    # to avoid including GL header files.
+    enum_defines = {
+        'GL_SYNC_GPU_COMMANDS_COMPLETE': 0x9117,
+      }
+    file.Write('\n')
+    for enum in enum_defines:
+      file.Write("#define %s 0x%x\n" % (enum, enum_defines[enum]))
+    file.Write('\n')
     for func in self.functions:
       if True:
       #gen_cmd = func.GetInfo('gen_cmd')
       #if gen_cmd == True or gen_cmd == None:
         func.WriteStruct(file)
     file.Write("\n")
     file.Close()
     self.generated_cpp_filenames.append(file.filename)
 
   def WriteDocs(self, filename):
@@ skipping 1142 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:]))