This CL keeps the alternate style size button pressed during a drag when:
- the user has dragged to the snap left / snap right buttons
- the user has dragged back to the size button

BUG=344411
TEST=AlternateFrameSizeButtonTest.*

Review URL: https://codereview.chromium.org/168943006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@252859 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 252859