Bug 1091008 - Factor out IsDataCachedToEndOfResource() into a higher-level question and answer it sensibly for MSE. r=cpearce

dom/media/MediaDecoder.cpp

@@ -679,11 +679,22 @@ void MediaDecoder::QueueMetadata(int64_t aPublishTime,
 }
 
 bool
-MediaDecoder::IsDataCachedToEndOfResource()
+MediaDecoder::IsExpectingMoreData()
 {
   ReentrantMonitorAutoEnter mon(GetReentrantMonitor());
-  return (mResource &&
-          mResource->IsDataCachedToEndOfResource(mDecoderPosition));
+
+  // If there's no resource, we're probably just getting set up.
+  if (!mResource) {
+    return true;
+  }
+
+  // If we've downloaded anything, we're not waiting for anything.
+  if (mResource->IsDataCachedToEndOfResource(mDecoderPosition)) {
+    return false;
+  }
+
+  // Otherwise, we should be getting data unless the stream is suspended.
+  return !mResource->IsSuspended();
 }
 
 void MediaDecoder::MetadataLoaded(MediaInfo* aInfo, MetadataTags* aTags)

dom/media/MediaDecoder.h

@@ -798,9 +798,12 @@ public:
   // Call on the main thread only.
   void FirstFrameLoaded();
 
-  // Returns true if the resource has been loaded. Acquires the monitor.
-  // Call from any thread.
-  virtual bool IsDataCachedToEndOfResource();
+  // Returns true if the this decoder is expecting any more data to arrive
+  // sometime in the not-too-distant future, either from the network or from
+  // an appendBuffer call on a MediaSource element.
+  //
+  // Acquires the monitor. Call from any thread.
+  virtual bool IsExpectingMoreData();
 
   // Called when the video has completed playing.
   // Call on the main thread only.

dom/media/MediaDecoderStateMachine.cpp

@@ -2421,9 +2421,8 @@ nsresult MediaDecoderStateMachine::RunStateMachine()
       if ((isLiveStream || !mDecoder->CanPlayThrough()) &&
             elapsed < TimeDuration::FromSeconds(mBufferingWait * mPlaybackRate) &&
             (mQuickBuffering ? HasLowDecodedData(QUICK_BUFFERING_LOW_DATA_USECS)
-                            : HasLowUndecodedData(mBufferingWait * USECS_PER_S)) &&
-            !mDecoder->IsDataCachedToEndOfResource() &&
-            !resource->IsSuspended())
+                             : HasLowUndecodedData(mBufferingWait * USECS_PER_S)) &&
+            mDecoder->IsExpectingMoreData())
       {
         DECODER_LOG("Buffering: wait %ds, timeout in %.3lfs %s",
                     mBufferingWait, mBufferingWait - elapsed.ToSeconds(),
@@ -2682,12 +2681,10 @@ void MediaDecoderStateMachine::AdvanceFrame()
 
   // Check to see if we don't have enough data to play up to the next frame.
   // If we don't, switch to buffering mode.
-  MediaResource* resource = mDecoder->GetResource();
   if (mState == DECODER_STATE_DECODING &&
       mDecoder->GetState() == MediaDecoder::PLAY_STATE_PLAYING &&
       HasLowDecodedData(remainingTime + EXHAUSTED_DATA_MARGIN_USECS) &&
-      !mDecoder->IsDataCachedToEndOfResource() &&
-      !resource->IsSuspended()) {
+      mDecoder->IsExpectingMoreData()) {
     if (JustExitedQuickBuffering() || HasLowUndecodedData()) {
       if (currentFrame) {
         VideoQueue().PushFront(currentFrame.forget());

dom/media/mediasource/MediaSourceDecoder.cpp

@@ -164,6 +164,13 @@ MediaSourceDecoder::Ended()
   mon.NotifyAll();
 }
 
+bool
+MediaSourceDecoder::IsExpectingMoreData()
+{
+  ReentrantMonitorAutoEnter mon(GetReentrantMonitor());
+  return !mReader->IsEnded();
+}
+
 void
 MediaSourceDecoder::SetMediaSourceDuration(double aDuration)
 {

dom/media/mediasource/MediaSourceDecoder.h

@@ -52,6 +52,7 @@ public:
   void OnTrackBufferConfigured(TrackBuffer* aTrackBuffer, const MediaInfo& aInfo);
 
   void Ended();
+  bool IsExpectingMoreData() MOZ_OVERRIDE;
 
   void SetMediaSourceDuration(double aDuration);