Move clearing of joining deadline back to onStopped

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=159421000

extensions/vp9/src/main/java/com/google/android/exoplayer2/ext/vp9/LibvpxVideoRenderer.java

@@ -478,11 +478,11 @@ public final class LibvpxVideoRenderer extends BaseRenderer {
   protected void onStarted() {
     droppedFrames = 0;
     droppedFrameAccumulationStartTimeMs = SystemClock.elapsedRealtime();
-    joiningDeadlineMs = C.TIME_UNSET;
   }
 
   @Override
   protected void onStopped() {
+    joiningDeadlineMs = C.TIME_UNSET;
     maybeNotifyDroppedFrames();
   }
 

library/core/src/main/java/com/google/android/exoplayer2/video/MediaCodecVideoRenderer.java

@@ -290,11 +290,11 @@ public class MediaCodecVideoRenderer extends MediaCodecRenderer {
     super.onStarted();
     droppedFrames = 0;
     droppedFrameAccumulationStartTimeMs = SystemClock.elapsedRealtime();
-    joiningDeadlineMs = C.TIME_UNSET;
   }
 
   @Override
   protected void onStopped() {
+    joiningDeadlineMs = C.TIME_UNSET;
     maybeNotifyDroppedFrames();
     super.onStopped();
   }