Revert 178494

Revert 178494
> Merge 177997
> > drive: Deal with the root directory same as others in MoveOperation.
> > 
> > Our current implementation of file moving is done in the following logic:
> > "if(source!=root) RemoveFrom(source); if(target!=root) AddTo(target)"
> > implicitly assuming "belonging to nowhere" means belonging to root.
> > But this is not the case.
> > 
> > This patch removes the "if !=root" checks and treats the root as same as other directories.
> > 
> > BUG=169420
> > TEST=Manually test the steps in the bug report.
> > 
> > Review URL: https://chromiumcodereview.appspot.com/12039005
> 
> TBR=kinaba@chromium.org
> Review URL: https://codereview.chromium.org/12049062

TBR=kinaba@chromium.org
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=178503