diff --git a/dom/serviceworkers/ServiceWorkerRegistration.cpp b/dom/serviceworkers/ServiceWorkerRegistration.cpp
index 6d620818d856..731543135fac 100644
--- a/dom/serviceworkers/ServiceWorkerRegistration.cpp
+++ b/dom/serviceworkers/ServiceWorkerRegistration.cpp
@@ -65,5 +65,70 @@ ServiceWorkerRegistration::CreateForWorker(WorkerPrivate* aWorkerPrivate,
   return registration.forget();
 }
 
+already_AddRefed<ServiceWorker>
+ServiceWorkerRegistration::GetInstalling() const
+{
+  RefPtr<ServiceWorker> ref = mInstallingWorker;
+  return ref.forget();
+}
+
+already_AddRefed<ServiceWorker>
+ServiceWorkerRegistration::GetWaiting() const
+{
+  RefPtr<ServiceWorker> ref = mWaitingWorker;
+  return ref.forget();
+}
+
+already_AddRefed<ServiceWorker>
+ServiceWorkerRegistration::GetActive() const
+{
+  RefPtr<ServiceWorker> ref = mActiveWorker;
+  return ref.forget();
+}
+
+void
+ServiceWorkerRegistration::UpdateState(const ServiceWorkerRegistrationDescriptor& aDescriptor)
+{
+  MOZ_DIAGNOSTIC_ASSERT(MatchesDescriptor(aDescriptor));
+
+  mDescriptor = aDescriptor;
+
+  nsCOMPtr<nsIGlobalObject> global = GetParentObject();
+  if (!global) {
+    mInstallingWorker = nullptr;
+    mWaitingWorker = nullptr;
+    mActiveWorker = nullptr;
+    return;
+  }
+
+  Maybe<ServiceWorkerDescriptor> active = aDescriptor.GetActive();
+  if (active.isSome()) {
+    mActiveWorker = global->GetOrCreateServiceWorker(active.ref());
+  } else {
+    mActiveWorker = nullptr;
+  }
+
+  Maybe<ServiceWorkerDescriptor> waiting = aDescriptor.GetWaiting();
+  if (waiting.isSome()) {
+    mWaitingWorker = global->GetOrCreateServiceWorker(waiting.ref());
+  } else {
+    mWaitingWorker = nullptr;
+  }
+
+  Maybe<ServiceWorkerDescriptor> installing = aDescriptor.GetInstalling();
+  if (installing.isSome()) {
+    mInstallingWorker = global->GetOrCreateServiceWorker(installing.ref());
+  } else {
+    mInstallingWorker = nullptr;
+  }
+}
+
+bool
+ServiceWorkerRegistration::MatchesDescriptor(const ServiceWorkerRegistrationDescriptor& aDescriptor) const
+{
+  return aDescriptor.PrincipalInfo() == mDescriptor.PrincipalInfo() &&
+         aDescriptor.Scope() == mDescriptor.Scope();
+}
+
 } // dom namespace
 } // mozilla namespace
diff --git a/dom/serviceworkers/ServiceWorkerRegistration.h b/dom/serviceworkers/ServiceWorkerRegistration.h
index e7d1378d6ae2..39ff2a40f34c 100644
--- a/dom/serviceworkers/ServiceWorkerRegistration.h
+++ b/dom/serviceworkers/ServiceWorkerRegistration.h
@@ -9,6 +9,7 @@
 
 #include "mozilla/DOMEventTargetHelper.h"
 #include "mozilla/dom/DOMPrefs.h"
+#include "mozilla/dom/ServiceWorker.h"
 #include "mozilla/dom/ServiceWorkerBinding.h"
 #include "mozilla/dom/ServiceWorkerRegistrationBinding.h"
 #include "mozilla/dom/ServiceWorkerRegistrationDescriptor.h"
@@ -43,14 +44,20 @@ public:
   JSObject*
   WrapObject(JSContext* aCx, JS::Handle<JSObject*> aGivenProto) override;
 
-  virtual already_AddRefed<ServiceWorker>
-  GetInstalling() = 0;
+  already_AddRefed<ServiceWorker>
+  GetInstalling() const;
 
-  virtual already_AddRefed<ServiceWorker>
-  GetWaiting() = 0;
+  already_AddRefed<ServiceWorker>
+  GetWaiting() const;
 
-  virtual already_AddRefed<ServiceWorker>
-  GetActive() = 0;
+  already_AddRefed<ServiceWorker>
+  GetActive() const;
+
+  void
+  UpdateState(const ServiceWorkerRegistrationDescriptor& aDescriptor);
+
+  bool
+  MatchesDescriptor(const ServiceWorkerRegistrationDescriptor& aDescriptor) const;
 
   virtual void
   GetScope(nsAString& aScope) const = 0;
@@ -85,6 +92,9 @@ protected:
   { }
 
   ServiceWorkerRegistrationDescriptor mDescriptor;
+  RefPtr<ServiceWorker> mInstallingWorker;
+  RefPtr<ServiceWorker> mWaitingWorker;
+  RefPtr<ServiceWorker> mActiveWorker;
 };
 
 
diff --git a/dom/serviceworkers/ServiceWorkerRegistrationImpl.cpp b/dom/serviceworkers/ServiceWorkerRegistrationImpl.cpp
index 280a83bb118f..f339757fc3cd 100644
--- a/dom/serviceworkers/ServiceWorkerRegistrationImpl.cpp
+++ b/dom/serviceworkers/ServiceWorkerRegistrationImpl.cpp
@@ -97,30 +97,6 @@ ServiceWorkerRegistrationMainThread::StopListeningForEvents()
   mListeningForEvents = false;
 }
 
-already_AddRefed<ServiceWorker>
-ServiceWorkerRegistrationMainThread::GetInstalling()
-{
-  MOZ_ASSERT(NS_IsMainThread());
-  RefPtr<ServiceWorker> ret = mInstallingWorker;
-  return ret.forget();
-}
-
-already_AddRefed<ServiceWorker>
-ServiceWorkerRegistrationMainThread::GetWaiting()
-{
-  MOZ_ASSERT(NS_IsMainThread());
-  RefPtr<ServiceWorker> ret = mWaitingWorker;
-  return ret.forget();
-}
-
-already_AddRefed<ServiceWorker>
-ServiceWorkerRegistrationMainThread::GetActive()
-{
-  MOZ_ASSERT(NS_IsMainThread());
-  RefPtr<ServiceWorker> ret = mActiveWorker;
-  return ret.forget();
-}
-
 void
 ServiceWorkerRegistrationMainThread::UpdateFound()
 {
@@ -130,38 +106,7 @@ ServiceWorkerRegistrationMainThread::UpdateFound()
 void
 ServiceWorkerRegistrationMainThread::UpdateState(const ServiceWorkerRegistrationDescriptor& aDescriptor)
 {
-  MOZ_DIAGNOSTIC_ASSERT(MatchesDescriptor(aDescriptor));
-
-  mDescriptor = aDescriptor;
-
-  nsCOMPtr<nsIGlobalObject> global = GetParentObject();
-  if (!global) {
-    mInstallingWorker = nullptr;
-    mWaitingWorker = nullptr;
-    mActiveWorker = nullptr;
-    return;
-  }
-
-  Maybe<ServiceWorkerDescriptor> active = aDescriptor.GetActive();
-  if (active.isSome()) {
-    mActiveWorker = global->GetOrCreateServiceWorker(active.ref());
-  } else {
-    mActiveWorker = nullptr;
-  }
-
-  Maybe<ServiceWorkerDescriptor> waiting = aDescriptor.GetWaiting();
-  if (waiting.isSome()) {
-    mWaitingWorker = global->GetOrCreateServiceWorker(waiting.ref());
-  } else {
-    mWaitingWorker = nullptr;
-  }
-
-  Maybe<ServiceWorkerDescriptor> installing = aDescriptor.GetInstalling();
-  if (installing.isSome()) {
-    mInstallingWorker = global->GetOrCreateServiceWorker(installing.ref());
-  } else {
-    mInstallingWorker = nullptr;
-  }
+  ServiceWorkerRegistration::UpdateState(aDescriptor);
 }
 
 void
@@ -178,8 +123,7 @@ ServiceWorkerRegistrationMainThread::RegistrationRemoved()
 bool
 ServiceWorkerRegistrationMainThread::MatchesDescriptor(const ServiceWorkerRegistrationDescriptor& aDescriptor)
 {
-  return aDescriptor.PrincipalInfo() == mDescriptor.PrincipalInfo() &&
-         aDescriptor.Scope() == mDescriptor.Scope();
+  return ServiceWorkerRegistration::MatchesDescriptor(aDescriptor);
 }
 
 namespace {
@@ -883,27 +827,6 @@ ServiceWorkerRegistrationWorkerThread::~ServiceWorkerRegistrationWorkerThread()
   MOZ_ASSERT(!mListener);
 }
 
-already_AddRefed<ServiceWorker>
-ServiceWorkerRegistrationWorkerThread::GetInstalling()
-{
-  // FIXME(nsm): Will be implemented after Bug 1113522.
-  return nullptr;
-}
-
-already_AddRefed<ServiceWorker>
-ServiceWorkerRegistrationWorkerThread::GetWaiting()
-{
-  // FIXME(nsm): Will be implemented after Bug 1113522.
-  return nullptr;
-}
-
-already_AddRefed<ServiceWorker>
-ServiceWorkerRegistrationWorkerThread::GetActive()
-{
-  // FIXME(nsm): Will be implemented after Bug 1113522.
-  return nullptr;
-}
-
 already_AddRefed<Promise>
 ServiceWorkerRegistrationWorkerThread::Update(ErrorResult& aRv)
 {
diff --git a/dom/serviceworkers/ServiceWorkerRegistrationImpl.h b/dom/serviceworkers/ServiceWorkerRegistrationImpl.h
index 35c38cba3da4..8a0a54ee9085 100644
--- a/dom/serviceworkers/ServiceWorkerRegistrationImpl.h
+++ b/dom/serviceworkers/ServiceWorkerRegistrationImpl.h
@@ -52,15 +52,6 @@ public:
   GetNotifications(const GetNotificationOptions& aOptions,
                    ErrorResult& aRv) override;
 
-  already_AddRefed<ServiceWorker>
-  GetInstalling() override;
-
-  already_AddRefed<ServiceWorker>
-  GetWaiting() override;
-
-  already_AddRefed<ServiceWorker>
-  GetActive() override;
-
   already_AddRefed<PushManager>
   GetPushManager(JSContext* aCx, ErrorResult& aRv) override;
 
@@ -141,14 +132,6 @@ private:
   const nsString mScope;
   bool mListeningForEvents;
 
-  // The following properties are cached here to ensure JS equality is satisfied
-  // instead of acquiring a new worker instance from the ServiceWorkerManager
-  // for every access. A null value is considered a cache miss.
-  // These three may change to a new worker at any time.
-  RefPtr<ServiceWorker> mInstallingWorker;
-  RefPtr<ServiceWorker> mWaitingWorker;
-  RefPtr<ServiceWorker> mActiveWorker;
-
   RefPtr<PushManager> mPushManager;
 };
 
@@ -185,15 +168,6 @@ public:
   GetNotifications(const GetNotificationOptions& aOptions,
                    ErrorResult& aRv) override;
 
-  already_AddRefed<ServiceWorker>
-  GetInstalling() override;
-
-  already_AddRefed<ServiceWorker>
-  GetWaiting() override;
-
-  already_AddRefed<ServiceWorker>
-  GetActive() override;
-
   void
   GetScope(nsAString& aScope) const override
   {