diff --git a/dom/workers/ServiceWorkerRegistrationInfo.cpp b/dom/workers/ServiceWorkerRegistrationInfo.cpp
index 06541257774e..a9b0cb184e0a 100644
--- a/dom/workers/ServiceWorkerRegistrationInfo.cpp
+++ b/dom/workers/ServiceWorkerRegistrationInfo.cpp
@@ -223,7 +223,7 @@ ServiceWorkerRegistrationInfo::TryToActivate()
   AssertIsOnMainThread();
   bool controlling = IsControllingDocuments();
   bool skipWaiting = mWaitingWorker && mWaitingWorker->SkipWaitingFlag();
-  bool idle = !mActiveWorker || mActiveWorker->WorkerPrivate()->IsIdle();
+  bool idle = IsIdle();
   if (idle && (!controlling || skipWaiting)) {
     Activate();
   }
@@ -519,4 +519,10 @@ ServiceWorkerRegistrationInfo::TransitionWaitingToActive()
                           WhichServiceWorker::ACTIVE_WORKER);
 }
 
+bool
+ServiceWorkerRegistrationInfo::IsIdle() const
+{
+  return !mActiveWorker || mActiveWorker->WorkerPrivate()->IsIdle();
+}
+
 END_WORKERS_NAMESPACE
diff --git a/dom/workers/ServiceWorkerRegistrationInfo.h b/dom/workers/ServiceWorkerRegistrationInfo.h
index 65d9f90a65d1..d2d217be0f68 100644
--- a/dom/workers/ServiceWorkerRegistrationInfo.h
+++ b/dom/workers/ServiceWorkerRegistrationInfo.h
@@ -171,6 +171,10 @@ public:
   // worker is updated to the Activating state.
   void
   TransitionWaitingToActive();
+
+  // Determine if the registration is actively performing work.
+  bool
+  IsIdle() const;
 };
 
 } // namespace workers