Fix BaseAudioContext::hasPendingActivity() to make it GCed correctly

third_party/WebKit/Source/modules/webaudio/AudioDestinationNode.cpp

Index: third_party/WebKit/Source/modules/webaudio/AudioDestinationNode.cpp
diff --git a/third_party/WebKit/Source/modules/webaudio/AudioDestinationNode.cpp b/third_party/WebKit/Source/modules/webaudio/AudioDestinationNode.cpp
index f4a86ca65181ee9dc233c803168a815022438191..a02406807862e9e17b8bd26b83f85bb59a341156 100644
--- a/third_party/WebKit/Source/modules/webaudio/AudioDestinationNode.cpp
+++ b/third_party/WebKit/Source/modules/webaudio/AudioDestinationNode.cpp
@@ -35,6 +35,7 @@ namespace blink {
 AudioDestinationHandler::AudioDestinationHandler(AudioNode& node, float sampleRate)
     : AudioHandler(NodeTypeDestination, node, sampleRate)
     , m_currentSampleFrame(0)
+    , m_numberOfConnections(0)
 {
     addInput();
 }
@@ -103,6 +104,14 @@ void AudioDestinationHandler::render(AudioBus* sourceBus, AudioBus* destinationB
     // Advance current sample-frame.
     size_t newSampleFrame = m_currentSampleFrame + numberOfFrames;
     releaseStore(&m_currentSampleFrame, newSampleFrame);
+
+    // Update connection status.
+    releaseStore(&m_numberOfConnections, input(0).numberOfRenderingConnections());
+}
+
+unsigned AudioDestinationHandler::numberOfConnections() const
+{
+    return acquireLoad(&m_numberOfConnections);
 }
 
 // ----------------------------------------------------------------
@@ -122,5 +131,10 @@ unsigned long AudioDestinationNode::maxChannelCount() const
     return audioDestinationHandler().maxChannelCount();
 }
 
+bool AudioDestinationNode::hasConnection() const
+{
+    return audioDestinationHandler().numberOfConnections() > 0;
+}

[Raymond Toy, 2016/08/26 20:12:15]

Since AudioDestinationNode is an AudioNode with a single input, can't this all
be done using audioDestinationHandler()->input(0)->isConnected()?  (See
PannerHandler::process for an example).

This gets rid of a lot of redundant stuff, if this actually works.

[hongchan, 2016/08/27 17:09:40]

As we discussed offline, this structure is necessary because the active
connection of the input summing junction can only be touched by the audio
rendering thread. So I am using the atomic access with a proxy variable, but
this causes the renderer crash in WebAudio layout tests.

+
 } // namespace blink