Implementation of 'AudioContext.getOutputTimestamp' method

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 f5eea247a774b645966ee5b6ccb6e35cf9056108..e9b2e168373c337ed38d0ed234164a18b5c6cf1c 100644
--- a/third_party/WebKit/Source/modules/webaudio/AudioDestinationNode.cpp
+++ b/third_party/WebKit/Source/modules/webaudio/AudioDestinationNode.cpp
@@ -23,6 +23,7 @@
  */
 
 #include "modules/webaudio/AudioDestinationNode.h"
+
 #include "modules/webaudio/AbstractAudioContext.h"
 #include "modules/webaudio/AudioNodeInput.h"
 #include "modules/webaudio/AudioNodeOutput.h"
@@ -44,8 +45,13 @@ AudioDestinationHandler::~AudioDestinationHandler()
     ASSERT(!isInitialized());
 }
 
-void AudioDestinationHandler::render(AudioBus* sourceBus, AudioBus* destinationBus, size_t numberOfFrames)
+void AudioDestinationHandler::render(AudioBus* sourceBus, AudioBus* destinationBus, size_t numberOfFrames, const WebAudioTimestamp& outputTimestamp)
 {
+    {
+        MutexLocker locker(m_mutex);

[Raymond Toy, 2016/06/14 16:42:40]

Can this be blocked by the main thread?  Generally, we use tryLocks to make sure
we don't block the audio thread.

[hongchan, 2016/06/14 17:10:38]

Consider to move this operation to context's pre-render task.

+        m_outputTimestamp = outputTimestamp;
+    }
+
     // We don't want denormals slowing down any of the audio processing
     // since they can very seriously hurt performance.
     // This will take care of all AudioNodes because they all process within this scope.
@@ -105,6 +111,12 @@ void AudioDestinationHandler::render(AudioBus* sourceBus, AudioBus* destinationB
     releaseStore(&m_currentSampleFrame, newSampleFrame);
 }
 
+WebAudioTimestamp AudioDestinationHandler::outputTimestamp() const
+{
+    MutexLocker locker(m_mutex);

[hongchan, 2016/06/14 17:10:38]

This will block the audio thread when the mutex is enabled.

+    return m_outputTimestamp;
+}
+
 // ----------------------------------------------------------------
 
 AudioDestinationNode::AudioDestinationNode(AbstractAudioContext& context)