Cherry-pick: Do not request vsync on touch if using synchronous compositor

Clean cherry-pick of chromium crrev.com/r289997

BUG: 17033041

Original description:

Nothing registers for the callback in WasShown if using
synchronous compositor, so this does not change any behavior.
So this is only removing unneeded RequestVSyncUpdate

Change-Id: I7346590b81f03adc31bbc8b8d067d5fe4590582b
1 file changed