Use ctrl-m for toggling minimize state for all windows

BUG=309915
R=flackr@chromium.org, jamescook@chromium.org
TBR=sky@chromium.org
TEST=manual. Ctrl-m should now toggle minimize state on browser as well as v2 apps.

Review URL: https://codereview.chromium.org/34583005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@230272 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 230272