Convert mojo::system::ChannelEndpointClient to use our new refcounting stuff (instead of base's).

mojo/edk/system/message_pipe.h

Index: mojo/edk/system/message_pipe.h
diff --git a/mojo/edk/system/message_pipe.h b/mojo/edk/system/message_pipe.h
index fc54199a69301d70118753914871543eea29c944..d7eefc6eb6e50cbafd0141b33d7941b4a1a9c407 100644
--- a/mojo/edk/system/message_pipe.h
+++ b/mojo/edk/system/message_pipe.h
@@ -39,19 +39,19 @@ class MessageInTransitQueue;
 class MessagePipe final : public ChannelEndpointClient {
  public:
   // Creates a |MessagePipe| with two new |LocalMessagePipeEndpoint|s.
-  static MessagePipe* CreateLocalLocal();
+  static RefPtr<MessagePipe> CreateLocalLocal();
 
   // Creates a |MessagePipe| with a |LocalMessagePipeEndpoint| on port 0 and a
   // |ProxyMessagePipeEndpoint| on port 1. |*channel_endpoint| is set to the
   // (newly-created) |ChannelEndpoint| for the latter.
-  static MessagePipe* CreateLocalProxy(
+  static RefPtr<MessagePipe> CreateLocalProxy(
       RefPtr<ChannelEndpoint>* channel_endpoint);
 
   // Similar to |CreateLocalProxy()|, except that it'll do so from an existing
   // |ChannelEndpoint| (whose |ReplaceClient()| it'll call) and take
   // |message_queue|'s contents as already-received incoming messages. If
   // |channel_endpoint| is null, this will create a "half-open" message pipe.
-  static MessagePipe* CreateLocalProxyFromExisting(
+  static RefPtr<MessagePipe> CreateLocalProxyFromExisting(
       MessageInTransitQueue* message_queue,
       RefPtr<ChannelEndpoint>&& channel_endpoint);
 
@@ -61,7 +61,7 @@ class MessagePipe final : public ChannelEndpointClient {
   // Note: This is really only needed in tests (outside of tests, this
   // configuration arises from a local message pipe having its port 0
   // "converted" using |ConvertLocalToProxy()|).
-  static MessagePipe* CreateProxyLocal(
+  static RefPtr<MessagePipe> CreateProxyLocal(
       RefPtr<ChannelEndpoint>* channel_endpoint);
 
   // Gets the other port number (i.e., 0 -> 1, 1 -> 0).
@@ -73,7 +73,7 @@ class MessagePipe final : public ChannelEndpointClient {
   static bool Deserialize(Channel* channel,
                           const void* source,
                           size_t size,
-                          scoped_refptr<MessagePipe>* message_pipe,
+                          RefPtr<MessagePipe>* message_pipe,
                           unsigned* port);
 
   // Gets the type of the endpoint (used for assertions, etc.).