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-Fades in the Contract ToolbarButton after the locationBarContainer has expanded.
-Fades in the Toolbar Buttons (Back,Fwd,ToolsMenu,etc.)
 after the locationBarContainer has contracted.
-Theres a delay to fade in the buttonsafter contraction/expansion, just like in the Old Animation.
-Fades out  the Toolbar Buttons (Back,Fwd,ToolsMenu,etc.) when the locationBarContainer
 expansion starts.

Video:
https://drive.google.com/open?id=1Re0-jdXUH11v-KccgKs2dEYX_fJ29Uud


Bug: 784592
Cq-Include-Trybots: master.tryserver.chromium.mac:ios-simulator-cronet;master.tryserver.chromium.mac:ios-simulator-full-configs
Change-Id: I473daf54dffb14a4da24ed58983ef7ab8b4981aa
Reviewed-on: https://chromium-review.googlesource.com/809706Reviewed-by: Gauthier Ambard <gambard@chromium.org>
Commit-Queue: Sergio Collazos <sczs@chromium.org>
Cr-Commit-Position: refs/heads/master@{#522461}