Reland "Omnibox UI Refresh: Implement popup open and close opacity animations."

This is a reland of 5cab33d1317a67d2512b8677a91611b5b5d18d91

In Patchset 2, it also makes the widget insensitive to mouse events
while animating closed.

This fixes the crash triggered when the user clicks on the results list
while the popup is animating closed. It also makes the popup no longer
change its highlighted match in response to mouseover events.

We also are insensitive to gesture events while closing, but we do not capture
them.

Original change's description:
> Omnibox UI Refresh: Implement popup open and close opacity animations.
>
> This eases in and out the Omnibox popup opacity over 82ms as it opens
> and closes. This matches the animation spec provided by UX.
>
> Bug: 823535
> Change-Id: Ic2add1f57f63ae6d043812f2bd5a766f84d302c9
> Reviewed-on: https://chromium-review.googlesource.com/1081198
> Commit-Queue: Tommy Li <tommycli@chromium.org>
> Reviewed-by: Peter Kasting <pkasting@chromium.org>
> Reviewed-by: Ali Juma <ajuma@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#564295}

TBR=ajuma@chromium.org

Bug: 823535, 857486
Change-Id: Ie497eefd007ae30a9098be30f55f63dc51adecc3
Reviewed-on: https://chromium-review.googlesource.com/1138514
Commit-Queue: Tommy Li <tommycli@chromium.org>
Reviewed-by: Justin Donnelly <jdonnelly@chromium.org>
Reviewed-by: Peter Kasting <pkasting@chromium.org>
Cr-Commit-Position: refs/heads/master@{#575706}
4 files changed