Fix nullptr deref in remote interface acquisition

ipc/ipc_channel_proxy.cc

 // Copyright (c) 2012 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_channel_proxy.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <utility>
@@ skipping 553 matching lines @@
   context()->AddGenericAssociatedInterfaceForIOThread(name, factory);
 }
 
 mojo::AssociatedGroup* ChannelProxy::GetAssociatedGroup() {
   return context()->associated_group();
 }
 
 void ChannelProxy::GetGenericRemoteAssociatedInterface(
     const std::string& name,
     mojo::ScopedInterfaceEndpointHandle handle) {
+  DCHECK(did_init_);
   context_->ipc_task_runner()->PostTask(
       FROM_HERE, base::Bind(&Context::GetRemoteAssociatedInterface,
                             context_.get(), name, base::Passed(&handle)));
 }
 
 void ChannelProxy::ClearIPCTaskRunner() {
   DCHECK(CalledOnValidThread());
 
   context()->ClearIPCTaskRunner();
 }
@@ skipping 29 matching lines @@
   return channel->TakeClientFileDescriptor();
 }
 #endif
 
 void ChannelProxy::OnChannelInit() {
 }
 
 //-----------------------------------------------------------------------------
 
 }  // namespace IPC