Keep AudioScheduledSourceNode alive until onended is called.

Source/modules/webaudio/AudioScheduledSourceNode.h

Index: Source/modules/webaudio/AudioScheduledSourceNode.h
diff --git a/Source/modules/webaudio/AudioScheduledSourceNode.h b/Source/modules/webaudio/AudioScheduledSourceNode.h
index 552fa0e75180ea09a107136d7e38de2fff382a3f..9f1788cb82dea149b5aa1fc86d52e9501d534421 100644
--- a/Source/modules/webaudio/AudioScheduledSourceNode.h
+++ b/Source/modules/webaudio/AudioScheduledSourceNode.h
@@ -54,6 +54,17 @@ public:
         FINISHED_STATE = 3
     };
 
+    // This helper class handles the lifetime of an AudioScheduledSourceNode with an onended event
+    // listener. This keeps the node alive until the event listener is processed.
+    class NotifyEndedTask {
+    public:
+        NotifyEndedTask(PassRefPtr<AudioScheduledSourceNode> scheduledNode);
+        void notifyEnded();
+
+    private:
+        RefPtr<AudioScheduledSourceNode> m_scheduledNode;
+    };
+
     AudioScheduledSourceNode(AudioContext*, float sampleRate);
 
     // Scheduling.
@@ -87,7 +98,6 @@ protected:
     virtual void finish();
 
     static void notifyEndedDispatch(void*);
-    void notifyEnded();
 
     PlaybackState m_playbackState;