Fix quick switch when swiping right on back button

Deferring the window tracking when touching down on the back button means that
we don't set isQuickSwitch before setting the state to FAST_OVERVIEW, making it
not scale up to be full screen. To fix this, we reapply the state when preparing
QuickScrubController for quick switch.

Change-Id: Ib3dcf300c45a00673ff9337f98d16d4e8cdf1ea0