GitLab

When dragging a tab out of a browser window (source window), the source
window scales down. The background behind the source window should be
the same blurred and darkened wallpaper as in overview.

See recorded video:
https://drive.google.com/open?id=1I_tXdQzUsiCwAqFikmZi9EywnUG1-wKl

Bug: 874266
Change-Id: Ie25dd3594fbcef37cda5c427e4daebf0ecffb1fd
Reviewed-on: https://chromium-review.googlesource.com/1185521Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Commit-Queue: Xiaoqian Dai <xdai@chromium.org>
Cr-Commit-Position: refs/heads/master@{#585295}