GitLab

Reason:
- Remove some complexity from file_manager.js
- Let FileTransferManager to mount gdata not having dependancy on FileManager.

BUG=127216
TEST=

Review URL: https://chromiumcodereview.appspot.com/10310163

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@138260 0039d316-1c4b-4281-b951-d872f2087c98