Bug 1283674 P1 Make ServiceWorkerContainer::GetController() work gracefully when its window is disconnected. r=baku

dom/workers/ServiceWorkerContainer.cpp

@@ -222,7 +222,6 @@ already_AddRefed<workers::ServiceWorker>
 ServiceWorkerContainer::GetController()
 {
   if (!mControllerWorker) {
-    nsresult rv;
     nsCOMPtr<nsIServiceWorkerManager> swm = mozilla::services::GetServiceWorkerManager();
     if (!swm) {
       return nullptr;
@@ -232,8 +231,8 @@ ServiceWorkerContainer::GetController()
     //       In theory the DOM ServiceWorker object can exist without the worker
     //       thread running, but it seems our design does not expect that.
     nsCOMPtr<nsISupports> serviceWorker;
-    rv = swm->GetDocumentController(GetOwner(),
-                                    getter_AddRefs(serviceWorker));
+    nsresult rv = swm->GetDocumentController(GetOwner(),
+                                             getter_AddRefs(serviceWorker));
     if (NS_WARN_IF(NS_FAILED(rv))) {
       return nullptr;
     }

dom/workers/ServiceWorkerManager.cpp

@@ -2328,7 +2328,10 @@ NS_IMETHODIMP
 ServiceWorkerManager::GetDocumentController(nsPIDOMWindowInner* aWindow,
                                             nsISupports** aServiceWorker)
 {
-  MOZ_ASSERT(aWindow);
+  if (NS_WARN_IF(!aWindow)) {
+    return NS_ERROR_DOM_INVALID_STATE_ERR;
+  }
+
   nsCOMPtr<nsIDocument> doc = aWindow->GetExtantDoc();
   if (!doc) {
     return NS_ERROR_DOM_INVALID_STATE_ERR;