Fix nullptr deref in remote interface acquisition

ipc/ipc_message_pipe_reader.cc

 // Copyright 2014 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 "ipc/ipc_message_pipe_reader.h"
 
 #include <stdint.h>
 
 #include <utility>
 
@@ skipping 98 matching lines @@
   result = mojo::WriteMessageNew(sender_pipe_, mojo_message->TakeMojoMessage(),
                                  MOJO_WRITE_MESSAGE_FLAG_NONE);
 
   DVLOG(4) << "Send " << message->type() << ": " << message->size();
   return result == MOJO_RESULT_OK;
 }
 
 void MessagePipeReader::GetRemoteInterface(
     const std::string& name,
     mojo::ScopedInterfaceEndpointHandle handle) {
+  if (!sender_.is_bound())
+    return;
   mojom::GenericInterfaceAssociatedRequest request;
   request.Bind(std::move(handle));
   sender_->GetAssociatedInterface(name, std::move(request));
 }
 
 void MessagePipeReader::SetPeerPid(int32_t peer_pid) {
   peer_pid_ = peer_pid;
   delegate_->OnPeerPidReceived();
 }
 
@@ skipping 34 matching lines @@
 
   Close();
 
   // NOTE: The delegate call below may delete |this|.
   if (delegate_)
     delegate_->OnPipeError();
 }
 
 }  // namespace internal
 }  // namespace IPC