Use depfiles for mojom generation.

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 218 matching lines @@
     else:
       args.import_directories[idx] = RelativePath(tokens[0], args.depth)
   generator_modules = LoadGenerators(args.generators_string)
 
   fileutil.EnsureDirectoryExists(args.output_dir)
 
   processor = MojomProcessor(lambda filename: filename in args.filename)
   processor.LoadTypemaps(set(args.typemaps))
   for filename in args.filename:
     processor.ProcessFile(args, remaining_args, generator_modules, filename)
+  if args.depfile:
+    assert args.depfile_target
+    with open(args.depfile, 'w') as f:
+      f.write('%s: %s' % (
+          args.depfile_target,
+          ' '.join(processor._parsed_files.keys())))
 
   return 0
 
 
 def _Precompile(args, _):
   generator_modules = LoadGenerators(",".join(_BUILTIN_GENERATORS.keys()))
 
   template_expander.PrecompileTemplates(generator_modules, args.output_dir)
   return 0
 
@@ skipping 46 matching lines @@
       "--export_attribute", type=str, default="",
       help="Optional attribute to specify on class declaration to export it "
       "for the component build.")
   generate_parser.add_argument(
       "--export_header", type=str, default="",
       help="Optional header to include in the generated headers to support the "
       "component build.")
   generate_parser.add_argument(
       "--generate_non_variant_code", action="store_true",
       help="Generate code that is shared by different variants.")
+  generate_parser.add_argument(
+      "--depfile", type=str,
+      help="A file into which the list of input files will be written.")
+  generate_parser.add_argument(
+      "--depfile_target", type=str,
+      help="The target name to use in the depfile.")
   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())