Move the Mac WebDragSource to use the TaskScheduler.

BUG=667892

Change-Id: I25c809655f4be1f170bcd07e25574766348c2de8
Reviewed-on: https://chromium-review.googlesource.com/575670
Reviewed-by: Erik Chen <erikchen@chromium.org>
Commit-Queue: Avi Drissman <avi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#487343}
1 file changed