Bug 1693306 - Simplify some uses of LookupOrInsertWith by GetOrInsertNew. r=xpcom-reviewers,necko-reviewers,dragana,nika

Differential Revision: https://phabricator.services.mozilla.com/D105479

accessible/generic/DocAccessible-inl.h

@@ -164,15 +164,9 @@ inline DocAccessible::AttrRelProviders* DocAccessible::GetOrCreateRelProviders(
   dom::DocumentOrShadowRoot* docOrShadowRoot =
       aElement->GetUncomposedDocOrConnectedShadowRoot();
   DependentIDsHashtable* hash =
-      mDependentIDsHashes
+      mDependentIDsHashes.GetOrInsertNew(docOrShadowRoot);
-          .LookupOrInsertWith(
-              docOrShadowRoot,
-              [] { return MakeUnique<DependentIDsHashtable>(); })
-          .get();
 
-  return hash
+  return hash->GetOrInsertNew(aID);
-      ->LookupOrInsertWith(aID, [] { return MakeUnique<AttrRelProviders>(); })
-      .get();
 }
 
 inline void DocAccessible::RemoveRelProvidersIfEmpty(dom::Element* aElement,

dom/base/DocumentOrShadowRoot.cpp

@@ -752,10 +752,7 @@ nsRadioGroupStruct* DocumentOrShadowRoot::GetRadioGroup(
 
 nsRadioGroupStruct* DocumentOrShadowRoot::GetOrCreateRadioGroup(
     const nsAString& aName) {
-  return mRadioGroups
+  return mRadioGroups.GetOrInsertNew(aName);
-      .LookupOrInsertWith(aName,
-                          [] { return MakeUnique<nsRadioGroupStruct>(); })
-      .get();
 }
 
 int32_t DocumentOrShadowRoot::StyleOrderIndexOfSheet(

dom/base/EventSourceEventService.cpp

@@ -201,11 +201,7 @@ EventSourceEventService::AddListener(uint64_t aInnerWindowID,
   }
   ++mCountListeners;
 
-  WindowListener* listener =
+  WindowListener* listener = mWindows.GetOrInsertNew(aInnerWindowID);
-      mWindows
-          .LookupOrInsertWith(aInnerWindowID,
-                              [] { return MakeUnique<WindowListener>(); })
-          .get();
 
   listener->mListeners.AppendElement(aListener);
 

dom/base/nsDOMMutationObserver.cpp

@@ -1039,11 +1039,7 @@ void nsAutoMutationBatch::Done() {
 
       if (allObservers.Length()) {
         auto* const transientReceivers =
-            ob->mTransientReceivers
+            ob->mTransientReceivers.GetOrInsertNew(removed);
-                .LookupOrInsertWith(
-                    removed,
-                    [] { return MakeUnique<nsCOMArray<nsMutationReceiver>>(); })
-                .get();
         for (uint32_t k = 0; k < allObservers.Length(); ++k) {
           nsMutationReceiver* r = allObservers[k];
           nsMutationReceiver* orig = r->GetParent() ? r->GetParent() : r;

dom/base/nsFrameMessageManager.cpp

@@ -239,15 +239,7 @@ void nsFrameMessageManager::AddMessageListener(const nsAString& aMessageName,
                                                MessageListener& aListener,
                                                bool aListenWhenClosed,
                                                ErrorResult& aError) {
-  auto* const listeners =
+  auto* const listeners = mListeners.GetOrInsertNew(aMessageName);
-      mListeners
-          .LookupOrInsertWith(
-              aMessageName,
-              [] {
-                return MakeUnique<
-                    nsAutoTObserverArray<nsMessageListenerInfo, 1>>();
-              })
-          .get();
   uint32_t len = listeners->Length();
   for (uint32_t i = 0; i < len; ++i) {
     MessageListener* strongListener = listeners->ElementAt(i).mStrongListener;
@@ -314,15 +306,7 @@ void nsFrameMessageManager::AddWeakMessageListener(
   }
 #endif
 
-  auto* const listeners =
+  auto* const listeners = mListeners.GetOrInsertNew(aMessageName);
-      mListeners
-          .LookupOrInsertWith(
-              aMessageName,
-              [] {
-                return MakeUnique<
-                    nsAutoTObserverArray<nsMessageListenerInfo, 1>>();
-              })
-          .get();
   uint32_t len = listeners->Length();
   for (uint32_t i = 0; i < len; ++i) {
     if (listeners->ElementAt(i).mWeakListener == weak) {

dom/broadcastchannel/BroadcastChannelService.cpp

@@ -81,12 +81,7 @@ void BroadcastChannelService::RegisterActor(
   AssertIsOnBackgroundThread();
   MOZ_ASSERT(aParent);
 
-  auto* const parents =
+  auto* const parents = mAgents.GetOrInsertNew(aOriginChannelKey);
-      mAgents
-          .LookupOrInsertWith(
-              aOriginChannelKey,
-              [] { return MakeUnique<nsTArray<BroadcastChannelParent*>>(); })
-          .get();
 
   MOZ_ASSERT(!parents->Contains(aParent));
   parents->AppendElement(aParent);

dom/commandhandler/nsCommandManager.cpp

@@ -81,11 +81,7 @@ nsCommandManager::AddCommandObserver(nsIObserver* aCommandObserver,
 
   // for each command in the table, we make a list of observers for that command
   auto* const commandObservers =
-      mObserversTable
+      mObserversTable.GetOrInsertNew(aCommandToObserve);
-          .LookupOrInsertWith(
-              aCommandToObserve,
-              [] { return mozilla::MakeUnique<ObserverList>(); })
-          .get();
 
   // need to check that this command observer hasn't already been registered
   int32_t existingIndex = commandObservers->IndexOf(aCommandObserver);

dom/indexedDB/ActorsParent.cpp

@@ -7627,13 +7627,7 @@ nsresult DatabaseConnection::UpdateRefcountFunction::ProcessValue(
     MOZ_ASSERT(id > 0);
 
     const auto entry =
-        WrapNotNull(mFileInfoEntries
+        WrapNotNull(mFileInfoEntries.GetOrInsertNew(id, file.FileInfoPtr()));
-                        .LookupOrInsertWith(id,
-                                            [&file] {
-                                              return MakeUnique<FileInfoEntry>(
-                                                  file.FileInfoPtr());
-                                            })
-                        .get());
 
     if (mInSavepoint) {
       mSavepointEntriesIndex.InsertOrUpdate(id, entry);

dom/localstorage/ActorsParent.cpp

@@ -3228,11 +3228,7 @@ bool RecvPBackgroundLSObserverConstructor(PBackgroundLSObserverParent* aActor,
   const auto notNullObserver = WrapNotNull(observer.get());
 
   nsTArray<NotNull<Observer*>>* const array =
-      gObservers
+      gObservers->GetOrInsertNew(notNullObserver->Origin());
-          ->LookupOrInsertWith(
-              notNullObserver->Origin(),
-              [] { return MakeUnique<nsTArray<NotNull<Observer*>>>(); })
-          .get();
   array->AppendElement(notNullObserver);
 
   if (RefPtr<Datastore> datastore = GetDatastore(observer->Origin())) {

dom/media/MediaManager.cpp

@@ -2792,11 +2792,7 @@ RefPtr<MediaManager::StreamPromise> MediaManager::GetUserMedia(
             // Add a WindowID cross-reference so OnNavigation can tear
             // things down
             nsTArray<nsString>* const array =
-                self->mCallIds
+                self->mCallIds.GetOrInsertNew(windowID);
-                    .LookupOrInsertWith(
-                        windowID,
-                        [] { return MakeUnique<nsTArray<nsString>>(); })
-                    .get();
             array->AppendElement(callID);
 
             nsCOMPtr<nsIObserverService> obs = services::GetObserverService();

dom/media/gmp/GMPMemoryStorage.cpp

@@ -13,10 +13,7 @@ class GMPMemoryStorage : public GMPStorage {
   GMPErr Open(const nsCString& aRecordName) override {
     MOZ_ASSERT(!IsOpen(aRecordName));
 
-    Record* record = mRecords
+    Record* record = mRecords.GetOrInsertNew(aRecordName);
-                         .LookupOrInsertWith(
-                             aRecordName, [] { return MakeUnique<Record>(); })
-                         .get();
     record->mIsOpen = true;
     return GMPNoErr;
   }

dom/presentation/PresentationServiceBase.h

@@ -79,10 +79,8 @@ class PresentationServiceBase {
         return;
       }
 
-      mRespondingSessionIds
+      mRespondingSessionIds.GetOrInsertNew(aWindowId)->AppendElement(
-          .LookupOrInsertWith(aWindowId,
+          nsString(aSessionId));
-                              [] { return MakeUnique<nsTArray<nsString>>(); })
-          ->AppendElement(nsString(aSessionId));
       mRespondingWindowIds.InsertOrUpdate(aSessionId, aWindowId);
     }
 
@@ -227,10 +225,8 @@ class PresentationServiceBase {
           for (uint32_t i = 0; i < entry->mListeners.Length(); ++i) {
             nsIPresentationAvailabilityListener* listener =
                 entry->mListeners.ObjectAt(i);
-            availabilityListenerTable
+            availabilityListenerTable.GetOrInsertNew(listener)->AppendElement(
-                .LookupOrInsertWith(
+                it.Key());
-                    listener, [] { return MakeUnique<nsTArray<nsString>>(); })
-                ->AppendElement(it.Key());
           }
         }
       }

dom/quota/ActorsParent.cpp

@@ -6674,11 +6674,7 @@ already_AddRefed<GroupInfo> QuotaManager::LockedGetOrCreateGroupInfo(
   mQuotaMutex.AssertCurrentThreadOwns();
   MOZ_ASSERT(aPersistenceType != PERSISTENCE_TYPE_PERSISTENT);
 
-  GroupInfoPair* const pair =
+  GroupInfoPair* const pair = mGroupInfoPairs.GetOrInsertNew(aGroup);
-      mGroupInfoPairs
-          .LookupOrInsertWith(aGroup,
-                              [] { return MakeUnique<GroupInfoPair>(); })
-          .get();
 
   RefPtr<GroupInfo> groupInfo = pair->LockedGetGroupInfo(aPersistenceType);
   if (!groupInfo) {

dom/serviceworkers/ServiceWorkerManager.cpp

@@ -1906,12 +1906,7 @@ void ServiceWorkerManager::AddScopeAndRegistration(
 
   MOZ_ASSERT(!scopeKey.IsEmpty());
 
-  auto* const data =
+  auto* const data = swm->mRegistrationInfos.GetOrInsertNew(scopeKey);
-      swm->mRegistrationInfos
-          .LookupOrInsertWith(
-              scopeKey,
-              [] { return MakeUnique<RegistrationDataPerPrincipal>(); })
-          .get();
 
   data->mScopeContainer.InsertScope(aScope);
   data->mInfos.InsertOrUpdate(aScope, RefPtr{aInfo});

dom/storage/StorageIPC.cpp

@@ -1463,11 +1463,7 @@ mozilla::ipc::IPCResult RecvPBackgroundLocalStorageCacheConstructor(
     gLocalStorageCacheParents = new LocalStorageCacheParentHashtable();
   }
 
-  gLocalStorageCacheParents
+  gLocalStorageCacheParents->GetOrInsertNew(aOriginKey)->AppendElement(actor);
-      ->LookupOrInsertWith(
-          aOriginKey,
-          [] { return MakeUnique<nsTArray<LocalStorageCacheParent*>>(); })
-      ->AppendElement(actor);
 
   // We are currently trusting the content process not to lie to us.  It is
   // future work to consult the ClientManager to determine whether this is a

dom/workers/RuntimeService.cpp

@@ -1222,12 +1222,7 @@ bool RuntimeService::RegisterWorker(WorkerPrivate& aWorkerPrivate) {
     if (!isServiceWorker) {
       // Service workers are excluded since their lifetime is separate from
       // that of dom windows.
-      if (auto* const windowArray =
+      if (auto* const windowArray = mWindowMap.GetOrInsertNew(window, 1);
-              mWindowMap
-                  .LookupOrInsertWith(
-                      window,
-                      [] { return MakeUnique<nsTArray<WorkerPrivate*>>(1); })
-                  .get();
           !windowArray->Contains(&aWorkerPrivate)) {
         windowArray->AppendElement(&aWorkerPrivate);
       } else {

layout/base/PresShell.cpp

@@ -10551,11 +10551,7 @@ void ReflowCountMgr::Add(const char* aName, nsIFrame* aFrame) {
   NS_ASSERTION(aName != nullptr, "Name shouldn't be null!");
 
   if (mDumpFrameCounts) {
-    auto* const counter =
+    auto* const counter = mCounts.GetOrInsertNew(aName, this);
-        mCounts
-            .LookupOrInsertWith(
-                aName, [this] { return MakeUnique<ReflowCounter>(this); })
-            .get();
     counter->Add();
   }
 

layout/base/nsCounterManager.cpp

@@ -308,10 +308,7 @@ bool nsCounterManager::AddCounterChanges(nsIFrame* aFrame) {
 
 nsCounterList* nsCounterManager::CounterListFor(nsAtom* aCounterName) {
   MOZ_ASSERT(aCounterName);
-  return mNames
+  return mNames.GetOrInsertNew(aCounterName);
-      .LookupOrInsertWith(aCounterName,
-                          [] { return MakeUnique<nsCounterList>(); })
-      .get();
 }
 
 void nsCounterManager::RecalcAll() {

layout/base/nsRefreshDriver.cpp

@@ -1354,11 +1354,7 @@ bool nsRefreshDriver::AddImageRequest(imgIRequest* aRequest) {
   if (delay == 0) {
     mRequests.PutEntry(aRequest);
   } else {
-    auto* const start =
+    auto* const start = mStartTable.GetOrInsertNew(delay);
-        mStartTable
-            .LookupOrInsertWith(delay,
-                                [] { return MakeUnique<ImageStartData>(); })
-            .get();
     start->mEntries.PutEntry(aRequest);
   }
 

layout/printing/nsPrintJob.cpp

@@ -2029,9 +2029,10 @@ void SelectionRangeState::SelectNodesExceptInSubtree(const Position& aStart,
   static constexpr auto kEllipsis = u"\x2026"_ns;
 
   nsINode* root = aStart.mNode->SubtreeRoot();
-  auto& start = mPositions.LookupOrInsertWith(root, [&] {
+  auto& start =
-    return Position{root, 0};
+      mPositions.WithEntryHandle(root, [&](auto&& entry) -> Position& {
-  });
+        return entry.OrInsertWith([&] { return Position{root, 0}; });
+      });
 
   bool ellipsizedStart = false;
   if (auto* text = Text::FromNode(aStart.mNode)) {

layout/style/ImageLoader.cpp

@@ -440,8 +440,7 @@ already_AddRefed<imgRequestProxy> ImageLoader::LoadImage(
   if (NS_FAILED(rv) || !request) {
     return nullptr;
   }
-  sImages->LookupOrInsertWith(request,
+  sImages->GetOrInsertNew(request);
-                              [] { return MakeUnique<ImageTableEntry>(); });
   return request.forget();
 }
 

layout/style/ShadowParts.cpp

@@ -106,9 +106,7 @@ ShadowParts ShadowParts::Parse(const nsAString& aString) {
       continue;
     }
     nsAtom* second = mapping.second.get();
-    parts.mMappings
+    parts.mMappings.GetOrInsertNew(mapping.first)
-        .LookupOrInsertWith(mapping.first,
-                            [] { return MakeUnique<PartList>(); })
         ->AppendElement(std::move(mapping.second));
     parts.mReverseMappings.InsertOrUpdate(second, std::move(mapping.first));
   }

netwerk/cache2/CacheFile.cpp

@@ -2195,9 +2195,7 @@ void CacheFile::QueueChunkListener(uint32_t aIndex,
   }
   item->mCallback = aCallback;
 
-  mChunkListeners
+  mChunkListeners.GetOrInsertNew(aIndex)->mItems.AppendElement(item);
-      .LookupOrInsertWith(aIndex, [] { return MakeUnique<ChunkListeners>(); })
-      ->mItems.AppendElement(item);
 }
 
 nsresult CacheFile::NotifyChunkListeners(uint32_t aIndex, nsresult aResult,

netwerk/dns/ChildDNSService.cpp

@@ -135,11 +135,7 @@ nsresult ChildDNSService::AsyncResolveInternal(
     nsCString key;
     GetDNSRecordHashKey(hostname, DNSResolverInfo::URL(aResolver), type,
                         aOriginAttributes, flags, originalListenerAddr, key);
-    mPendingRequests
+    mPendingRequests.GetOrInsertNew(key)->AppendElement(sender);
-        .LookupOrInsertWith(
-            key,
-            [] { return MakeUnique<nsTArray<RefPtr<DNSRequestSender>>>(); })
-        ->AppendElement(sender);
   }
 
   sender->StartRequest();

netwerk/dns/DNSPacket.cpp

@@ -860,8 +860,7 @@ nsresult DNSPacket::DecodeInternal(
 
     auto parseRecord = [&]() {
       LOG(("Parsing additional record type: %u", type));
-      auto& entry = aAdditionalRecords.LookupOrInsertWith(
+      auto* entry = aAdditionalRecords.GetOrInsertNew(qname);
-          qname, [] { return MakeUnique<DOHresp>(); });
 
       switch (type) {
         case TRRTYPE_A:

netwerk/dns/nsDNSService2.cpp

@@ -1434,9 +1434,7 @@ nsDNSService::ReportFailedSVCDomainName(const nsACString& aOwnerName,
                                         const nsACString& aSVCDomainName) {
   MutexAutoLock lock(mLock);
 
-  mFailedSVCDomainNames
+  mFailedSVCDomainNames.GetOrInsertNew(aOwnerName, 1)
-      .LookupOrInsertWith(aOwnerName,
-                          [] { return MakeUnique<nsTArray<nsCString>>(1); })
       ->AppendElement(aSVCDomainName);
   return NS_OK;
 }

netwerk/protocol/http/PendingTransactionQueue.cpp

@@ -57,14 +57,11 @@ void PendingTransactionQueue::InsertTransactionNormal(
 
   uint64_t windowId = TabIdForQueuing(info->Transaction());
   nsTArray<RefPtr<PendingTransactionInfo>>* const infoArray =
-      mPendingTransactionTable
+      mPendingTransactionTable.GetOrInsertNew(windowId);
-          .LookupOrInsertWith(
-              windowId,
-              [] {
-                return MakeUnique<nsTArray<RefPtr<PendingTransactionInfo>>>();
-              })
-          .get();
 
+  // XXX At least if a new array was empty before, this isn't efficient, as it
+  // does an insert-sort. It would be better to just append all elements and
+  // then sort.
   InsertTransactionSorted(*infoArray, info, aInsertAsFirstForTheSamePriority);
 }
 

netwerk/protocol/http/nsHttpConnectionMgr.cpp

@@ -3344,11 +3344,8 @@ void nsHttpConnectionMgr::RegisterOriginCoalescingKey(HttpConnectionBase* conn,
 
   nsCString newKey;
   BuildOriginFrameHashKey(newKey, ci, host, port);
-  mCoalescingHash
+  mCoalescingHash.GetOrInsertNew(newKey, 1)->AppendElement(
-      .LookupOrInsertWith(newKey,
+      do_GetWeakReference(static_cast<nsISupportsWeakReference*>(conn)));
-                          [] { return MakeUnique<nsTArray<nsWeakPtr>>(1); })
-      ->AppendElement(
-          do_GetWeakReference(static_cast<nsISupportsWeakReference*>(conn)));
 
   LOG(
       ("nsHttpConnectionMgr::RegisterOriginCoalescingKey "

netwerk/streamconv/nsStreamConverterService.cpp

@@ -119,14 +119,9 @@ nsresult nsStreamConverterService::AddAdjacency(const char* aContractID) {
   // each MIME-type is represented as a key in our hashtable.
 
   nsTArray<RefPtr<nsAtom>>* const fromEdges =
-      mAdjacencyList
+      mAdjacencyList.GetOrInsertNew(fromStr);
-          .LookupOrInsertWith(
-              fromStr,
-              [] { return mozilla::MakeUnique<nsTArray<RefPtr<nsAtom>>>(); })
-          .get();
 
-  mozilla::Unused << mAdjacencyList.LookupOrInsertWith(
+  mAdjacencyList.GetOrInsertNew(toStr);
-      toStr, [] { return mozilla::MakeUnique<nsTArray<RefPtr<nsAtom>>>(); });
 
   // Now we know the FROM and TO types are represented as keys in the hashtable.
   // Let's "connect" the verticies, making an edge.

toolkit/components/filewatcher/NativeFileWatcherWin.cpp

@@ -1098,10 +1098,7 @@ void NativeFileWatcherIOTask::AppendCallbacksToHashtables(
     const nsMainThreadPtrHandle<nsINativeFileWatcherErrorCallback>&
         aOnErrorHandle) {
   ChangeCallbackArray* const callbacksArray =
-      mChangeCallbacksTable
+      mChangeCallbacksTable.GetOrInsertNew(aPath);
-          .LookupOrInsertWith(aPath,
-                              [] { return MakeUnique<ChangeCallbackArray>(); })
-          .get();
 
   // Now we do have an entry for that path. Check to see if the callback is
   // already there.
@@ -1115,10 +1112,7 @@ void NativeFileWatcherIOTask::AppendCallbacksToHashtables(
 
   // Same thing for the error callback.
   ErrorCallbackArray* const errorCallbacksArray =
-      mErrorCallbacksTable
+      mErrorCallbacksTable.GetOrInsertNew(aPath);
-          .LookupOrInsertWith(aPath,
-                              [] { return MakeUnique<ErrorCallbackArray>(); })
-          .get();
 
   ErrorCallbackArray::index_type errorCallbackIndex =
       errorCallbacksArray->IndexOf(aOnErrorHandle);

toolkit/components/telemetry/core/TelemetryEvent.cpp

@@ -375,10 +375,7 @@ bool IsExpired(const EventKey& key) { return key.id == kExpiredEventId; }
 
 EventRecordArray* GetEventRecordsForProcess(const StaticMutexAutoLock& lock,
                                             ProcessID processType) {
-  return gEventRecords
+  return gEventRecords.GetOrInsertNew(uint32_t(processType));
-      .LookupOrInsertWith(uint32_t(processType),
-                          [] { return MakeUnique<EventRecordArray>(); })
-      .get();
 }
 
 EventKey* GetEventKey(const StaticMutexAutoLock& lock,

toolkit/components/telemetry/core/TelemetryScalar.cpp

@@ -1514,10 +1514,7 @@ nsresult internal_GetScalarByEnum(const StaticMutexAutoLock& lock,
   // Get the process-specific storage or create one if it's not
   // available.
   ScalarStorageMapType* const scalarStorage =
-      processStorage
+      processStorage.GetOrInsertNew(storageId);
-          .LookupOrInsertWith(storageId,
-                              [] { return MakeUnique<ScalarStorageMapType>(); })
-          .get();
 
   // Check if the scalar is already allocated in the parent or in the child
   // storage.
@@ -1798,10 +1795,7 @@ nsresult internal_GetKeyedScalarByEnum(const StaticMutexAutoLock& lock,
   // Get the process-specific storage or create one if it's not
   // available.
   KeyedScalarStorageMapType* const scalarStorage =
-      processStorage
+      processStorage.GetOrInsertNew(storageId);
-          .LookupOrInsertWith(
-              storageId, [] { return MakeUnique<KeyedScalarStorageMapType>(); })
-          .get();
 
   if (scalarStorage->Get(aId.id, &scalar)) {
     *aRet = scalar;

widget/android/EventDispatcher.cpp

@@ -868,11 +868,7 @@ nsresult EventDispatcher::IterateEvents(JSContext* aCx, JS::HandleValue aEvents,
 
 nsresult EventDispatcher::RegisterEventLocked(
     const nsAString& aEvent, nsIAndroidEventListener* aListener) {
-  ListenersList* list =
+  ListenersList* list = mListenersMap.GetOrInsertNew(aEvent);
-      mListenersMap
-          .LookupOrInsertWith(aEvent,
-                              [] { return MakeUnique<ListenersList>(); })
-          .get();
 
 #ifdef DEBUG
   for (ssize_t i = 0; i < list->listeners.Count(); i++) {

widget/gtk/WakeLockListener.cpp

@@ -483,11 +483,7 @@ nsresult WakeLockListener::Callback(const nsAString& topic,
     return NS_OK;
 
   WakeLockTopic* const topicLock =
-      mTopics
+      mTopics.GetOrInsertNew(topic, topic, mConnection);
-          .LookupOrInsertWith(
-              topic,
-              [&] { return MakeUnique<WakeLockTopic>(topic, mConnection); })
-          .get();
 
   // Treat "locked-background" the same as "unlocked" on desktop linux.
   bool shouldLock = state.EqualsLiteral("locked-foreground");

xpcom/components/nsComponentManager.cpp

@@ -726,10 +726,7 @@ void nsComponentManagerImpl::ManifestComponent(ManifestProcessingContext& aCx,
     return;
   }
 
-  KnownModule* const km =
+  KnownModule* const km = mKnownModules.GetOrInsertNew(hash, fl);
-      mKnownModules
-          .LookupOrInsertWith(hash, [&] { return MakeUnique<KnownModule>(fl); })
-          .get();
 
   void* place = mArena.Allocate(sizeof(nsCID));
   nsID* permanentCID = static_cast<nsID*>(place);