Gallery: Apply aspect settings immediately when pressing the aspect buttons.
Previously the aspect ratio is applied at the beginning of dragging after
pressing the buttons.
The CL also temporarily removes dimmable class from the container of aspect
buttons to prevent the aspect buttons from being dimmed until a user starts
dragging.
BUG=401312
TEST=manually
Review URL: https://codereview.chromium.org/
454743002
Cr-Commit-Position: refs/heads/master@{#288320}
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@288320 0039d316-1c4b-4281-b951-d872f2087c98