Restores maximized browser before dragging a tab.
Allows a tab dragged out of a maximized browser to get properly side-snapped (similar to how docking is allowed).

BUG=319205

Review URL: https://codereview.chromium.org/80323002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@238236 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 238236