GitLab

Previously it was OverviewWindowDragController who is responsible to
remove the window from overview before trying to snap it. It should be
SplitViewController's responsibility to do this work.

Bug: None
Change-Id: I157d8cff294fd43ecbefeff01fc20cd61cb95361
Reviewed-on: https://chromium-review.googlesource.com/1008966
Commit-Queue: Xiaoqian Dai <xdai@chromium.org>
Reviewed-by: Mitsuru Oshima <oshima@chromium.org>
Cr-Commit-Position: refs/heads/master@{#550441}