Bug 1434342 P3 Make each ServiceWorker DOM object automatically fire its statechange event when appropriate. r=asuth

dom/serviceworkers/ServiceWorker.cpp

@@ -107,7 +107,11 @@ ServiceWorker::State() const
 void
 ServiceWorker::SetState(ServiceWorkerState aState)
 {
+  ServiceWorkerState oldState = mDescriptor.State();
   mDescriptor.SetState(aState);
+  if (oldState != aState) {
+    DOMEventTargetHelper::DispatchTrustedEvent(NS_LITERAL_STRING("statechange"));
+  }
 }
 
 void
@@ -116,12 +120,6 @@ ServiceWorker::GetScriptURL(nsString& aURL) const
   CopyUTF8toUTF16(mDescriptor.ScriptURL(), aURL);
 }
 
-void
-ServiceWorker::DispatchStateChange(ServiceWorkerState aState)
-{
-  DOMEventTargetHelper::DispatchTrustedEvent(NS_LITERAL_STRING("statechange"));
-}
-
 void
 ServiceWorker::PostMessage(JSContext* aCx, JS::Handle<JS::Value> aMessage,
                            const Sequence<JSObject*>& aTransferable,

dom/serviceworkers/ServiceWorker.h

@@ -47,9 +47,6 @@ public:
   void
   GetScriptURL(nsString& aURL) const;
 
-  void
-  DispatchStateChange(ServiceWorkerState aState);
-
 #ifdef XP_WIN
 #undef PostMessage
 #endif

dom/serviceworkers/ServiceWorkerInfo.cpp

@@ -159,16 +159,9 @@ public:
 
   NS_IMETHOD Run() override
   {
-    // We need to update the state of all instances atomically before notifying
-    // them to make sure that the observed state for all instances inside
-    // statechange event handlers is correct.
     for (size_t i = 0; i < mInstances.Length(); ++i) {
       mInstances[i]->SetState(mState);
     }
-    for (size_t i = 0; i < mInstances.Length(); ++i) {
-      mInstances[i]->DispatchStateChange(mState);
-    }
-
     return NS_OK;
   }