[Draft] try out the idea of adding export macros for C++ bindings.

mojo/public/tools/bindings/mojom_bindings_generator.py

 #!/usr/bin/env python
 # Copyright 2013 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.
 
 """The frontend for the Mojo bindings system."""
 
 
 import argparse
 import imp
@@ skipping 125 matching lines @@
     module.path = os.path.relpath(os.path.abspath(filename),
                                   os.path.abspath(args.depth))
 
     # Normalize to unix-style path here to keep the generators simpler.
     module.path = module.path.replace('\\', '/')
 
     if self._should_generate(filename):
       for language, generator_module in generator_modules.iteritems():
         generator = generator_module.Generator(
             module, args.output_dir, typemap=self._typemap.get(language, {}),
-            variant=args.variant, bytecode_path=args.bytecode_path)
+            variant=args.variant, bytecode_path=args.bytecode_path,
+            dll_export_declaration=args.dll_export_declaration,
+            dll_export_include=args.dll_export_include)
         filtered_args = []
         if hasattr(generator_module, 'GENERATOR_PREFIX'):
           prefix = '--' + generator_module.GENERATOR_PREFIX + '_'
           filtered_args = [arg for arg in remaining_args
                            if arg.startswith(prefix)]
         generator.GenerateFiles(filtered_args)
 
     # Save result.
     self._processed_files[filename] = module
     return module
@@ skipping 88 matching lines @@
   generate_parser.add_argument("--typemap", action="append", metavar="TYPEMAP",
                                default=[], dest="typemaps",
                                help="apply TYPEMAP to generated output")
   generate_parser.add_argument("--variant", dest="variant", default=None,
                                help="output a named variant of the bindings")
   generate_parser.add_argument(
       "--bytecode_path", type=str, required=True, help=(
           "the path from which to load template bytecode; to generate template "
           "bytecode, run %s precompile BYTECODE_PATH" % os.path.basename(
               sys.argv[0])))
+  generate_parser.add_argument(
+      "--dll_export_declaration", type=str,
+      help="TODO(yzshen)")
+  generate_parser.add_argument(
+      "--dll_export_include", type=str,
+      help="TODO(yzshen)")
   generate_parser.set_defaults(func=_Generate)
 
   precompile_parser = subparsers.add_parser("precompile",
       description="Precompile templates for the mojom bindings generator.")
   precompile_parser.add_argument(
       "-o", "--output_dir", dest="output_dir", default=".",
       help="output directory for precompiled templates")
   precompile_parser.set_defaults(func=_Precompile)
 
   args, remaining_args = parser.parse_known_args()
   return args.func(args, remaining_args)
 
 
 if __name__ == "__main__":
   sys.exit(main())