Bug 1112822 - Don't allow MP4Reader to decode if someone shut it down. r=mattwoodrow

dom/media/fmp4/MP4Reader.cpp

@@ -525,6 +525,14 @@ MP4Reader::RequestVideoData(bool aSkipToNextKeyframe,
   MOZ_ASSERT(GetTaskQueue()->IsCurrentThreadIn());
   VLOG("RequestVideoData skip=%d time=%lld", aSkipToNextKeyframe, aTimeThreshold);
 
+  if (mShutdown) {
+    NS_WARNING("RequestVideoData on shutdown MP4Reader!");
+    MonitorAutoLock lock(mVideo.mMonitor);
+    nsRefPtr<VideoDataPromise> p = mVideo.mPromise.Ensure(__func__);
+    p->Reject(CANCELED, __func__);
+    return p;
+  }
+
   MOZ_ASSERT(HasVideo() && mPlatform && mVideo.mDecoder);
 
   bool eos = false;
@@ -555,7 +563,12 @@ MP4Reader::RequestAudioData()
   VLOG("RequestAudioData");
   MonitorAutoLock lock(mAudio.mMonitor);
   nsRefPtr<AudioDataPromise> p = mAudio.mPromise.Ensure(__func__);
-  ScheduleUpdate(kAudio);
+  if (!mShutdown) {
+    ScheduleUpdate(kAudio);
+  } else {
+    NS_WARNING("RequestAudioData on shutdown MP4Reader!");
+    p->Reject(CANCELED, __func__);
+  }
   return p;
 }