Gin: Make it easier to implement Wrappable

gin/function_template.h

Index: gin/function_template.h
diff --git a/gin/function_template.h b/gin/function_template.h
index 7e33994eedbacf7b9ee79a22ffb0e7c50c0f7c09..44fec3c6f7c538b40439a08ce2788220c9c26394 100644
--- a/gin/function_template.h
+++ b/gin/function_template.h
@@ -55,10 +55,9 @@ struct CallbackParamTraits<const T*> {
 // It inherits from Wrappable, which delete itself when both (a) the refcount
 // via base::RefCounted has dropped to zero, and (b) there are no more
 // JavaScript references in V8.
-class CallbackHolderBase : public Wrappable {
- public:
-  virtual WrapperInfo* GetWrapperInfo() OVERRIDE;
-  static WrapperInfo kWrapperInfo;
+//
+// TODO(aa): Do we still need the separate base class?
+class CallbackHolderBase : public Wrappable<CallbackHolderBase> {
  protected:
   virtual ~CallbackHolderBase() {}
 };