Blink implementation of PushManager#hasPermission()

public/platform/WebCallbacks.h

Index: public/platform/WebCallbacks.h
diff --git a/public/platform/WebCallbacks.h b/public/platform/WebCallbacks.h
index 20cf3bbaa401d3e9122c0ab18a1d7052eeb68495..eaad1f1be5cf40d3363aa15dad60c6b026fb8bf7 100644
--- a/public/platform/WebCallbacks.h
+++ b/public/platform/WebCallbacks.h
@@ -49,6 +49,15 @@ public:
     virtual void onError(T*) { };
 };
 
+
+template<typename S>
+class WebCallbacks<S, void> {
+public:
+    virtual ~WebCallbacks() { };
+    virtual void onSuccess(S*) { };
+    virtual void onError() { };
+};
+
 } // namespace blink
 
 #endif