Remove implicit conversions from scoped_refptr to T* in mojo/

mojo/system/proxy_message_pipe_endpoint.h

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef MOJO_SYSTEM_PROXY_MESSAGE_PIPE_ENDPOINT_H_
 #define MOJO_SYSTEM_PROXY_MESSAGE_PIPE_ENDPOINT_H_
 
 #include <stdint.h>
 
 #include "base/compiler_specific.h"
@@ skipping 50 matching lines @@
 
  private:
   void Detach();
 
 #ifdef NDEBUG
   void AssertConsistentState() const {}
 #else
   void AssertConsistentState() const;
 #endif
 
-  bool is_attached() const { return !!channel_; }
+  bool is_attached() const { return !!channel_.get(); }
 
   bool is_running() const {
     return remote_id_ != MessageInTransit::kInvalidEndpointId;
   }
 
   // This should only be set if we're attached.
   scoped_refptr<Channel> channel_;
 
   // |local_id_| should be set to something other than
   // |MessageInTransit::kInvalidEndpointId| when we're attached.
@@ skipping 11 matching lines @@
   // not ready to send them yet.
   MessageInTransitQueue paused_message_queue_;
 
   DISALLOW_COPY_AND_ASSIGN(ProxyMessagePipeEndpoint);
 };
 
 }  // namespace system
 }  // namespace mojo
 
 #endif  // MOJO_SYSTEM_PROXY_MESSAGE_PIPE_ENDPOINT_H_