Use main looper for onFrameRenderListener in Media codec CTS

Previously the current looper was implicitly used, but it does not
seem to exist in some context.

Instead, use the main looper and mark the primitives variables
concurrently accessed as volatile.

The bug was introduced by: I02c7f44365bcbf628e14e093638981ca14fd688e.

Bug: 160105641
Test: cts -m CtsMediaTestCases -t android.media.cts.DecoderTest#testTunneledVideoFlush
Change-Id: Ib6be4180ff7cc879ba1f1c32a32ce2b96e063db0
1 file changed