[WONT COMMIT] ServiceWorker: Move unregister function from WebSWProvider to WebSWRegistration (1/3)

public/platform/WebServiceWorkerRegistration.h

Index: public/platform/WebServiceWorkerRegistration.h
diff --git a/public/platform/WebServiceWorkerRegistration.h b/public/platform/WebServiceWorkerRegistration.h
index 908a209ae4560d8ec54147b2675ae4ed01c4b61f..8195fde46cf2cd7f7d67cfc0bd7f0e11fa398a28 100644
--- a/public/platform/WebServiceWorkerRegistration.h
+++ b/public/platform/WebServiceWorkerRegistration.h
@@ -5,14 +5,18 @@
 #ifndef WebServiceWorkerRegistration_h
 #define WebServiceWorkerRegistration_h
 
+#include "public/platform/WebCallbacks.h"
 #include "public/platform/WebURL.h"
 
 namespace blink {
 
 class WebServiceWorkerRegistrationProxy;
+struct WebServiceWorkerError;
 
 class WebServiceWorkerRegistration {
 public:
+    using UnregisterCallbacks = WebCallbacks<bool, WebServiceWorkerError>;
+
     virtual ~WebServiceWorkerRegistration() { }
 
     virtual void setProxy(WebServiceWorkerRegistrationProxy*) { }
@@ -20,6 +24,7 @@ public:
     virtual void proxyStopped() { }
 
     virtual WebURL scope() const { return WebURL(); }
+    virtual void unregister(UnregisterCallbacks*) { }
 };
 
 } // namespace blink