Add depfile support to android build scripts

build/android/gyp/gcc_preprocess.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.
 
 import optparse
 import os
 import sys
 
@@ skipping 13 matching lines @@
       '-I', options.include_path,
       '-o', options.output,
       options.template
       ])
 
   build_utils.CheckOutput(gcc_cmd)
 
 
 def main():
   parser = optparse.OptionParser()
+  build_utils.AddDepfileOption(parser)
+
   parser.add_option('--include-path', help='Include path for gcc.')
   parser.add_option('--template', help='Path to template.')
   parser.add_option('--output', help='Path for generated file.')
   parser.add_option('--stamp', help='Path to touch on success.')
   parser.add_option('--defines', help='Pre-defines macros', action='append')
 
   options, _ = parser.parse_args()
 
   DoGcc(options)
 
+  if options.depfile:
+    build_utils.WriteDepfile(
+        options.depfile,
+        build_utils.GetPythonDependencies())
+
   if options.stamp:
     build_utils.Touch(options.stamp)
 
 
 if __name__ == '__main__':
   sys.exit(main())