Add a test to cover service worker update codepath when extension is updated

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 bac9ab620847a693819b127887f6107fcea28f66..8a48a921c11b870e34127efa162fdef25b7cf61c 100644
--- a/content/public/browser/service_worker_context.h
+++ b/content/public/browser/service_worker_context.h
@@ -70,6 +70,10 @@ class ServiceWorkerContext {
   virtual void DeleteForOrigin(const GURL& origin_url,
                                const ResultCallback& callback) = 0;
 
+  // Forces updating of ServiceWorker before next page load.
+  // Used to clear stale ServiceWorker when an extension is updated.
+  virtual void SetForceUpdateOnPageLoadForOrigin(const GURL& origin) = 0;
+
   // Returns true if a Service Worker registration exists that matches |url|,
   // and if |other_url| falls inside the scope of the same registration. Note
   // this still returns true even if there is a Service Worker registration