ash: Add UMA action metrics for Ctrl-Shift-Q

BUG=none
TEST=uma.googleplex.com gains a user action entry from Accel_Exit_First_Q and Accel_Exit_Second_Q
R=sschmitz@chromium.org
TBR=sschmitz@chromium.org

Review URL: https://chromiumcodereview.appspot.com/15841006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@202421 0039d316-1c4b-4281-b951-d872f2087c98
5 files changed