SyncFS: Remove dead code


BUG=n/a
TEST=n/a

Review URL: https://codereview.chromium.org/109993002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@239483 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 239483