Merge "Adds a null check in NuPlayer::closeAudioSink."

media/libmediaplayerservice/nuplayer/NuPlayer.cpp

@@ -1798,7 +1798,9 @@ void NuPlayer::tryOpenAudioSinkForOffload(
 }
 
 void NuPlayer::closeAudioSink() {
-    mRenderer->closeAudioSink();
+    if (mRenderer != NULL) {
+        mRenderer->closeAudioSink();
+    }
 }
 
 void NuPlayer::restartAudio(