[ServiceWorker] Introduce isControlledByServiceWorker() in FrameLoaderClient and WebFrameClient

public/web/WebFrameClient.h

Index: public/web/WebFrameClient.h
diff --git a/public/web/WebFrameClient.h b/public/web/WebFrameClient.h
index ff19656543895482adacd59ac393e9a90383450a..502bf6bef7060d3ea3ab43b2c2504114c4e025c0 100644
--- a/public/web/WebFrameClient.h
+++ b/public/web/WebFrameClient.h
@@ -566,6 +566,11 @@ public:
     // Notifies embedder about an accessibility event.
     virtual void postAccessibilityEvent(const WebAXObject&, WebAXEvent) { }
 
+    // ServiceWorker -------------------------------------------------------
+
+    // Whether the frame is controlled by the ServiceWorker
+    virtual bool isControlledByServiceWorker() { return false; }
+
 protected:
     virtual ~WebFrameClient() { }
 };