GitLab

Completes shield opacity animation after overview closes.

This CL deals with the transition into and out of the overview
mode.
When the shelf is in SHELF_BACKGROUND_MAXIMIZED state the shield starts
black and animates to 70% black.
When the shelf is transparent or semi-transparent the shield starts
transparent and animates to 70% black.
When overview mode finishes an observer is installed on the shield
widget that deletes itself and the widget once the opacity animation
completes.

BUG=624443

Review-Url: https://codereview.chromium.org/2141133002
Cr-Commit-Position: refs/heads/master@{#406122}