Makes dragging all the tabs in a maximized window restore it

On windows we were previously letting the OS do it, but this leads to
some problems with the tabs not resizing. Fix is to enable the
ash code path. Additionally I'm making revert go back to maximized in
this case.

BUG=333788
TEST=see bug
R=varkha@chromium.org

Review URL: https://codereview.chromium.org/145333002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@246646 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 246646