Parallelize SkLightDeferredCanvas:

SkMutex(fCondVar1) manages recording thread and SkCondVar(fCondVar2) manages
the flush and playback thread . fCondVar2 waits in flush recording and playback
upon reading a flush command signals using fCondVar2 thereby releasing the wait.

Currently playback of flush is causing a thread wait forcing the flashcanvas
to hang. As a workaround, we stopped recording of flush and directly invoking canvas
flush . Chromium and native flashcanvas work with this workaround. Work is in progress
to record and playback flush command as well.