file_manager: Allow users to delete files/directories under My Drive even when offline

BUG=260542
TEST=Disconnect from network and try to delete files from Google Drive on Files.app

Review URL: https://codereview.chromium.org/69863002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@237340 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 237340