Fix MediaSourcePlayer unittests and minor code cleanup.

media/base/android/media_source_player.h

Index: media/base/android/media_source_player.h
diff --git a/media/base/android/media_source_player.h b/media/base/android/media_source_player.h
index decc5cc7c0aee79b3213569520f6ed02b32e41f7..0ed6221ba1e2b31b61b985f446e63e4862e01dc3 100644
--- a/media/base/android/media_source_player.h
+++ b/media/base/android/media_source_player.h
@@ -111,7 +111,10 @@ class MEDIA_EXPORT MediaSourcePlayer : public MediaPlayerAndroid {
   void OnDecoderStarved();
 
   // Starts the |decoder_starvation_callback_| task with the timeout value.
-  void StartStarvationCallback(const base::TimeDelta& timeout);
+  // |presentation_timestamp| - The presentation timestamp used for starvation
+  // timeout computations. It represents the timestamp of the last piece of
+  // decoded data.
+  void StartStarvationCallback(const base::TimeDelta& presentation_timestamp);
 
   // Schedules a seek event in |pending_events_| and calls StopDecode() on all
   // the MediaDecoderJobs.