Shut down the ServiceWorker system as the browser's shutting down.

content/public/browser/service_worker_context.h

Index: content/public/browser/service_worker_context.h
diff --git a/content/public/browser/service_worker_context.h b/content/public/browser/service_worker_context.h
index a701d6c7a56176168fc9593f05c025d2cea70db7..2d0805e9b99ec1dfbd25220660a1cffeaa528b8c 100644
--- a/content/public/browser/service_worker_context.h
+++ b/content/public/browser/service_worker_context.h
@@ -49,6 +49,11 @@ class ServiceWorkerContext {
 
   // TODO(jyasskin): Provide a way to SendMessage to a Scope.
 
+  // Synchronously releases all of the RenderProcessHosts that have Service
+  // Workers running inside them, and prevents any new Service Worker instances
+  // from starting up.
+  virtual void Terminate() = 0;
+
  protected:
   ServiceWorkerContext() {}
   virtual ~ServiceWorkerContext() {}