GitLab

They were inconsistently sent from different places,
which led to this bug because DragResizer isn't used in multi window resizer.
They should be sent from single soruce.

BUG=b/72402303
TEST=Covered by unit tests. Also tested manually. See bug for repro step.

Change-Id: If9e24b7b62d879a83607ee99634c2670645c7bb6
Reviewed-on: https://chromium-review.googlesource.com/885081
Commit-Queue: Mitsuru Oshima <oshima@chromium.org>
Reviewed-by: Dominik Laskowski <domlaskowski@chromium.org>
Cr-Commit-Position: refs/heads/master@{#532263}