GitLab

To have the correct behavior when a submenu
is opened via a HoverButton, the HoverButton
class is transformed into a subclass of
MenuButton.

HoverButton can now function as both, a normal
button and a menu button.

Visible changes in the user menu:
 - When the submenu is opened, the button stays
 highlighted.
 - When the submenu closes, the button loses its
 highlighting.

Video from before:
https://drive.google.com/file/d/1QONj3SZv-zAwQ2r7WqF4Ww7UKo0wVcJ2/view?usp=sharing
Video from after:
https://drive.google.com/file/d/1dwh_68A0cjiK2kiPnHwCvSdQX6RByVY5/view?usp=sharing

Bug: 814809
Change-Id: I6401cb39d20fca9c3590a67bd0fbeff5a2043b83
Reviewed-on: https://chromium-review.googlesource.com/953623Reviewed-by: Scott Violet <sky@chromium.org>
Reviewed-by: Mihai Sardarescu <msarda@chromium.org>
Commit-Queue: Thomas Tangl <tangltom@chromium.org>
Cr-Commit-Position: refs/heads/master@{#543061}