Enable showing the toolkit-views simplified fullscreen UI on Mac.
Puts the new simplified fullscreen UI behind
chrome://flags/#simplified-fullscreen-ui on Mac.
It uses the toolkit-views UI, since it's already written and works
pretty well. Only few things need to be farmed out to the delegate
since the bubble can't assume its parent is a views::Widget.
Fixes a quirk where opacity-animating bubbles would briefly change
their bounds to have zero-height and back during construction. (We
complain about visible but zero-sized Widgets on Mac).
If this all works we can delete some ~700 lines of Cocoa code when
this simplified fullscreen UI is default on Mac.
BUG=352425
Review URL: https://codereview.chromium.org/1654723002
Cr-Commit-Position: refs/heads/master@{#373386}
8 files changed
