am ea5d7a9d: move File and Difference classes into common script

Merge commit 'ea5d7a9de7660bef5b9c68f6372a92d4b2f2f1f6' into gingerbread-plus-aosp

* commit 'ea5d7a9de7660bef5b9c68f6372a92d4b2f2f1f6':
  move File and Difference classes into common script