Fix shelf blur snapping in/out.

As opposed to animating opacity, set the opacity of the layer
containing blur before or after the animation.  We cannot
animate the opacity of a layer which has blur because this
causes blur to snap away.

Bug: 881134

Change-Id: I33f12d985fa0198dfe6c66c3f67a8128e1e611fc
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1578068
Commit-Queue: Alex Newcomer <newcomer@chromium.org>
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#653837}
2 files changed