Fixed zoom bubble showing up behind app menu in hosted apps.

Previously, this only worked in browser windows. Now, it uses the button
provider to detect if the menu is open, in either browser or hosted app
windows.

Bug: 791399
Change-Id: I885a4979e729eaedbb647903209c54b63286da22
Reviewed-on: https://chromium-review.googlesource.com/991892
Commit-Queue: Matt Giuca <mgiuca@chromium.org>
Reviewed-by: Bret Sepulveda <bsep@chromium.org>
Cr-Commit-Position: refs/heads/master@{#549458}
1 file changed