--- a/dom/interfaces/base/nsIServiceWorkerManager.idl
+++ b/dom/interfaces/base/nsIServiceWorkerManager.idl
@@ -24,19 +24,29 @@ interface nsIServiceWorkerUnregisterCall
   void unregisterFailed();
 };
 
 interface nsIWorkerDebugger;
 
 [scriptable, builtinclass, uuid(76e357ed-208d-4e4c-9165-1c4059707879)]
 interface nsIServiceWorkerInfo : nsISupports
 {
+  // State values below should match the ServiceWorkerState enumeration.
+  const unsigned short STATE_INSTALLING = 0;
+  const unsigned short STATE_INSTALLED = 1;
+  const unsigned short STATE_ACTIVATING = 2;
+  const unsigned short STATE_ACTIVATED = 3;
+  const unsigned short STATE_REDUNDANT = 4;
+  const unsigned short STATE_UNKNOWN = 5;
+
   readonly attribute DOMString scriptSpec;
   readonly attribute DOMString cacheName;
 
+  readonly attribute unsigned short state;
+
   readonly attribute nsIWorkerDebugger debugger;
 
   void attachDebugger();
 
   void detachDebugger();
 };
 
 [scriptable, uuid(87e63548-d440-4b8a-b158-65ad1de0211E)]

--- a/dom/workers/ServiceWorkerInfo.cpp
+++ b/dom/workers/ServiceWorkerInfo.cpp
@@ -5,16 +5,29 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #include "ServiceWorkerInfo.h"
 
 #include "ServiceWorkerScriptCache.h"
 
 BEGIN_WORKERS_NAMESPACE
 
+static_assert(nsIServiceWorkerInfo::STATE_INSTALLING == static_cast<uint16_t>(ServiceWorkerState::Installing),
+              "ServiceWorkerState enumeration value should match state values from nsIServiceWorkerInfo.");
+static_assert(nsIServiceWorkerInfo::STATE_INSTALLED == static_cast<uint16_t>(ServiceWorkerState::Installed),
+              "ServiceWorkerState enumeration value should match state values from nsIServiceWorkerInfo.");
+static_assert(nsIServiceWorkerInfo::STATE_ACTIVATING == static_cast<uint16_t>(ServiceWorkerState::Activating),
+              "ServiceWorkerState enumeration value should match state values from nsIServiceWorkerInfo.");
+static_assert(nsIServiceWorkerInfo::STATE_ACTIVATED == static_cast<uint16_t>(ServiceWorkerState::Activated),
+              "ServiceWorkerState enumeration value should match state values from nsIServiceWorkerInfo.");
+static_assert(nsIServiceWorkerInfo::STATE_REDUNDANT == static_cast<uint16_t>(ServiceWorkerState::Redundant),
+              "ServiceWorkerState enumeration value should match state values from nsIServiceWorkerInfo.");
+static_assert(nsIServiceWorkerInfo::STATE_UNKNOWN == static_cast<uint16_t>(ServiceWorkerState::EndGuard_),
+              "ServiceWorkerState enumeration value should match state values from nsIServiceWorkerInfo.");
+
 NS_IMPL_ISUPPORTS(ServiceWorkerInfo, nsIServiceWorkerInfo)
 
 NS_IMETHODIMP
 ServiceWorkerInfo::GetScriptSpec(nsAString& aScriptSpec)
 {
   AssertIsOnMainThread();
   CopyUTF8toUTF16(mScriptSpec, aScriptSpec);
   return NS_OK;
@@ -24,16 +37,25 @@ NS_IMETHODIMP
 ServiceWorkerInfo::GetCacheName(nsAString& aCacheName)
 {
   AssertIsOnMainThread();
   aCacheName = mCacheName;
   return NS_OK;
 }
 
 NS_IMETHODIMP
+ServiceWorkerInfo::GetState(uint16_t* aState)
+{
+  MOZ_ASSERT(aState);
+  AssertIsOnMainThread();
+  *aState = static_cast<uint16_t>(mState);
+  return NS_OK;
+}
+
+NS_IMETHODIMP
 ServiceWorkerInfo::GetDebugger(nsIWorkerDebugger** aResult)
 {
   if (NS_WARN_IF(!aResult)) {
     return NS_ERROR_FAILURE;
   }
 
   return mServiceWorkerPrivate->GetDebugger(aResult);
 }