Fix quick scrub skipping more than one page

There was a race condition where we were getting onQuickScrubProgress
before onQuickScrubStart. If we got enough of those, we were jumping
some pages before the block is set in onQuickScrubStart (which also adds
its own page jump). Now we don't send any onQuickScrubProgress() to
QuickScrubController until we have sent onQuickScrubStart()

Bug: 118636260
Change-Id: I60084850b0b1baad34112ab5945fce81cc3a3c53