Remove implicit conversions from scoped_refptr to T* in mojo/

mojo/system/proxy_message_pipe_endpoint.cc

 // 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.
 
 #include "mojo/system/proxy_message_pipe_endpoint.h"
 
 #include <string.h>
 
 #include "base/logging.h"
 #include "mojo/system/channel.h"
@@ skipping 65 matching lines @@
     message->set_destination_id(remote_id_);
     if (!channel_->WriteMessage(message.Pass()))
       LOG(WARNING) << "Failed to write message to channel";
   } else {
     paused_message_queue_.AddMessage(message.Pass());
   }
 }
 
 void ProxyMessagePipeEndpoint::Attach(scoped_refptr<Channel> channel,
                                       MessageInTransit::EndpointId local_id) {
-  DCHECK(channel);
+  DCHECK(channel.get());
   DCHECK_NE(local_id, MessageInTransit::kInvalidEndpointId);
 
   DCHECK(!is_attached());
 
   AssertConsistentState();
   channel_ = channel;
   local_id_ = local_id;
   AssertConsistentState();
 }
 
@@ skipping 42 matching lines @@
     DCHECK_NE(local_id_, MessageInTransit::kInvalidEndpointId);
   } else {  // Not attached.
     DCHECK_EQ(local_id_, MessageInTransit::kInvalidEndpointId);
     DCHECK_EQ(remote_id_, MessageInTransit::kInvalidEndpointId);
   }
 }
 #endif
 
 }  // namespace system
 }  // namespace mojo