Revert 225008 "Fix a threading bug in the brlapi basec braille c..."

> Fix a threading bug in the brlapi basec braille controller
> 
> This CL enables brlapi support by default in builds for chromeos (it's already enabled by default in chromeos itself, so that part is a noop). This revealed a threading bug in the implementation which is also fixed my moving a file_path_watcher from the IO thread to the FILE threadd.
> 
> BUG=178559
> 
> Review URL: https://chromiumcodereview.appspot.com/24325002

TBR=plundblad@chromium.org

Review URL: https://codereview.chromium.org/23537068

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@225011 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 225011