RefCounted types should not have public destructors

ipc/ipc_sender.h

Index: ipc/ipc_sender.h
diff --git a/ipc/ipc_sender.h b/ipc/ipc_sender.h
index f70f709c9ffe6932bdb85b5aadb9cb3d1649db39..9c26bf3e204047e7a952dfdc45caed6cc3b43664 100644
--- a/ipc/ipc_sender.h
+++ b/ipc/ipc_sender.h
@@ -13,13 +13,14 @@ class Message;
 
 class IPC_EXPORT Sender {
  public:
-  virtual ~Sender() {}
-
   // Sends the given IPC message.  The implementor takes ownership of the
   // given Message regardless of whether or not this method succeeds.  This
   // is done to make this method easier to use.  Returns true on success and
   // false otherwise.
   virtual bool Send(Message* msg) = 0;
+
+ protected:
+  virtual ~Sender() {}
 };
 
 }  // namespace IPC