Fix invalid depfile generation in generate_split_manifest.py

build/android/gyp/generate_split_manifest.py

 #!/usr/bin/env python
 #
 # Copyright 2015 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.
 """Creates an AndroidManifest.xml for an APK split.
 
 Given the manifest file for the main APK, generates an AndroidManifest.xml with
 the value required for a Split APK (package, versionCode, etc).
 """
@@ skipping 72 matching lines @@
       main_manifest,
       options.split,
       options.has_code)
 
   with file(options.out_manifest, 'w') as f:
     f.write(split_manifest)
 
   if options.depfile:
     build_utils.WriteDepfile(
         options.depfile,
-        [main_manifest] + build_utils.GetPythonDependencies())
+        [options.main_manifest] + build_utils.GetPythonDependencies())
 
 
 if __name__ == '__main__':
   main()