Bug 1413604 P2 Make WorkerHolderToken use an nsTObserverArray to allow for mutation during iteration. r=asuth

dom/workers/WorkerHolderToken.cpp

@@ -96,14 +96,17 @@ WorkerHolderToken::Notify(Status aStatus)
     return true;
   }
 
-  mShuttingDown = true;
-
   // Start the asynchronous destruction of our actors.  These will call back
   // into RemoveActor() once the actor is destroyed.
-  for (uint32_t i = 0; i < mListenerList.Length(); ++i) {
-    mListenerList[i]->WorkerShuttingDown();
+  nsTObserverArray<Listener*>::ForwardIterator iter(mListenerList);
+  while (iter.HasMore()) {
+    iter.GetNext()->WorkerShuttingDown();
   }
 
+  // Set this after calling WorkerShuttingDown() on listener list in case
+  // one callback triggers another listener to be added.
+  mShuttingDown = true;
+
   return true;
 }
 

dom/workers/WorkerHolderToken.h

@@ -8,7 +8,7 @@
 #define mozilla_dom_workers_WorkerHolderToken_h
 
 #include "nsISupportsImpl.h"
-#include "nsTArray.h"
+#include "nsTObserverArray.h"
 #include "WorkerHolder.h"
 
 BEGIN_WORKERS_NAMESPACE
@@ -67,7 +67,7 @@ private:
   virtual bool
   Notify(workers::Status aStatus) override;
 
-  nsTArray<Listener*> mListenerList;
+  nsTObserverArray<Listener*> mListenerList;
   const Status mShutdownStatus;
   bool mShuttingDown;