[Chromecast] Ignore MonitorLoop if EOS in unit test

chromecast/media/cma/backend/audio_video_pipeline_device_unittest.cc

Index: chromecast/media/cma/backend/audio_video_pipeline_device_unittest.cc
diff --git a/chromecast/media/cma/backend/audio_video_pipeline_device_unittest.cc b/chromecast/media/cma/backend/audio_video_pipeline_device_unittest.cc
index f2552950ca8ee7546abaf25ad17c38db6d17e040..8512370526f61ee203fd49540c8e808b34951a1c 100644
--- a/chromecast/media/cma/backend/audio_video_pipeline_device_unittest.cc
+++ b/chromecast/media/cma/backend/audio_video_pipeline_device_unittest.cc
@@ -376,6 +376,10 @@ void AudioVideoPipelineDeviceTest::OnPushBufferComplete(
 }
 
 void AudioVideoPipelineDeviceTest::MonitorLoop() {
+  // Backend is stopped, no need to monitor the loop any more.
+  if (audio_decoder_ == nullptr && video_decoder_ == nullptr)
+    return;
+
   base::TimeDelta media_time =
       base::TimeDelta::FromMicroseconds(backend_->GetCurrentPts());