Don't run removeFinishedSourceNodes with the context lock.

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

Index: third_party/WebKit/Source/modules/webaudio/BaseAudioContext.cpp
diff --git a/third_party/WebKit/Source/modules/webaudio/BaseAudioContext.cpp b/third_party/WebKit/Source/modules/webaudio/BaseAudioContext.cpp
index 44c5badf83d62db681b89090707876641dba8236..f051751d309fd1e9de967651888f83de18070a05 100644
--- a/third_party/WebKit/Source/modules/webaudio/BaseAudioContext.cpp
+++ b/third_party/WebKit/Source/modules/webaudio/BaseAudioContext.cpp
@@ -646,7 +646,7 @@ void BaseAudioContext::removeFinishedSourceNodes() {
   m_finishedSourceNodes.clear();
 }
 
-void BaseAudioContext::releaseFinishedSourceNodes() {
+bool BaseAudioContext::releaseFinishedSourceNodes() {
   ASSERT(isGraphOwner());
   DCHECK(isAudioThread());
   bool didRemove = false;
@@ -662,13 +662,7 @@ void BaseAudioContext::releaseFinishedSourceNodes() {
       }
     }
   }
-  if (didRemove)
-    Platform::current()->mainThread()->getWebTaskRunner()->postTask(
-        BLINK_FROM_HERE,
-        crossThreadBind(&BaseAudioContext::removeFinishedSourceNodes,
-                        wrapCrossThreadPersistent(this)));
-
-  m_finishedSourceHandlers.clear();

[hongchan, 2017/01/19 12:47:43]

We don't have this line in the patchset anymore. Is that okay?

[Raymond Toy, 2017/01/20 19:36:10]

Fixed.

+  return didRemove;
 }
 
 void BaseAudioContext::notifySourceNodeStartedProcessing(AudioNode* node) {
@@ -741,18 +735,26 @@ void BaseAudioContext::handlePostRenderTasks() {
   // is that there will be some nodes which will take slightly longer than usual
   // to be deleted or removed from the render graph (in which case they'll
   // render silence).
+  bool didRemove = false;
   if (tryLock()) {
     // Take care of AudioNode tasks where the tryLock() failed previously.
     deferredTaskHandler().breakConnections();
 
     // Dynamically clean up nodes which are no longer needed.
-    releaseFinishedSourceNodes();
+    didRemove = releaseFinishedSourceNodes();
 
     deferredTaskHandler().handleDeferredTasks();
     deferredTaskHandler().requestToDeleteHandlersOnMainThread();
 
     unlock();
   }
+
+  if (didRemove) {
+    Platform::current()->mainThread()->getWebTaskRunner()->postTask(
+        BLINK_FROM_HERE,
+        crossThreadBind(&BaseAudioContext::removeFinishedSourceNodes,
+                        wrapCrossThreadPersistent(this)));
+  }
 }
 
 void BaseAudioContext::resolvePromisesForResumeOnMainThread() {