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This change:
1) Adds support to MenuClosureAnimationMac for animating menu closure without
   animating selecting an item;
2) Has MenuController use MenuClosureAnimationMac to animate cancels caused by
   outside clicks

Bug: 833856
Change-Id: I9743b396798e4b125c038b35decc9aceb083926d
Reviewed-on: https://chromium-review.googlesource.com/1231837
Commit-Queue: Elly Fong-Jones <ellyjones@chromium.org>
Reviewed-by: Scott Violet <sky@chromium.org>
Cr-Commit-Position: refs/heads/master@{#594738}