GitLab

This is a reland of 3abaa7f0.

Changes: Now that the observer observes the new layer, on window
destroying or removing from root window we should stop animating the
new window as well.

Original change's description:
> wm: Improve cross fade animation.
>
> *Destroy old layer when new layer animation is aborted.
> *Only log histograms once after animation.
>
> The old layer is owned by a observer which does not know when the new
> layer is being aborted. Change this so that the observer observers the
> new layer and destroys the old layer accordingly.
>
> The pass animations reporter will be used for every LayerAnimationElement,
> for cross fade, we animate opacity in addition to transform when the old
> bounds is wider than the new bounds. This results in double counting,
> which skews the smoothness numbers as animating two properties should be
> slower.
>
> Test: manual, ash_unittests WindowAnimationsTest.CrossFadeHistograms
> Bug: 868170, 1087460
> Change-Id: I3bc5b597e8109a3e87f432f6aa352ba94860f8ed
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2218557
> Reviewed-by: Mitsuru Oshima <oshima@chromium.org>
> Commit-Queue: Sammie Quon <sammiequon@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#773397}

Bug: 868170, 1087460, 1088169
Change-Id: I3a2f6af334ca0cd325e49107e812824f7a39340e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2224990Reviewed-by: Mitsuru Oshima <oshima@chromium.org>
Commit-Queue: Sammie Quon <sammiequon@chromium.org>
Cr-Commit-Position: refs/heads/master@{#773921}