ServiceWorker: Make skipWaiting only works on documents using current registration

content/browser/service_worker/service_worker_provider_host.cc

Index: content/browser/service_worker/service_worker_provider_host.cc
diff --git a/content/browser/service_worker/service_worker_provider_host.cc b/content/browser/service_worker/service_worker_provider_host.cc
index 2bb6499487916db409c6eecbd9c10cae0863b7e2..3494214cedc9b55aed3d432a85d66218778bc161 100644
--- a/content/browser/service_worker/service_worker_provider_host.cc
+++ b/content/browser/service_worker/service_worker_provider_host.cc
@@ -84,6 +84,11 @@ void ServiceWorkerProviderHost::OnRegistrationFailed(
 void ServiceWorkerProviderHost::OnSkippedWaiting(
     ServiceWorkerRegistration* registration) {
   DCHECK_EQ(associated_registration_.get(), registration);
+  // A client is using a registration if it is controlled by the active worker
+  // of the registration. skipWaiting doesn't cause a client to start using
+  // the registration.

[falken, 2014/12/15 06:18:01]

Since "using" is a normal English word, it would make it more clear that this is
sentence is a definition by saying:
A client is said to be "using" a registration...

+  if (!controlling_version_)
+    return;
   ServiceWorkerVersion* active_version = registration->active_version();
   DCHECK_EQ(active_version->status(), ServiceWorkerVersion::ACTIVATING);
   SetControllerVersionAttribute(active_version);