HLS: misc bug fixes

- fix no target-duration case

- fix for audio-only <=> audio/video switching

- disable audio-only variants if there is at least
  one variant with video

- fix mpeg2ts PTS wraparound when bandwidth adapting

- tweak up/down switch marks

bug: 19567254

Change-Id: Ib46144203c56dfc96eccd6ddaa3867e8a4f2c6a9
diff --git a/media/libmedia/IStreamSource.cpp b/media/libmedia/IStreamSource.cpp
index d480aef..840e453 100644
--- a/media/libmedia/IStreamSource.cpp
+++ b/media/libmedia/IStreamSource.cpp
@@ -35,6 +35,9 @@
 // static
 const char *const IStreamListener::kKeyMediaTimeUs = "media-time-us";
 
+// static
+const char *const IStreamListener::kKeyRecentMediaTimeUs = "recent-media-time-us";
+
 enum {
     // IStreamSource
     SET_LISTENER = IBinder::FIRST_CALL_TRANSACTION,