Mojo C++ bindings: remove usage of AssociatedGroup from ipc/

ipc/ipc_channel_mojo.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_channel_mojo.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <memory>
@@ skipping 450 matching lines @@
         std::move(unwrapped_attachment));
     DCHECK(ok);
     if (!ok) {
       LOG(ERROR) << "Failed to add new Mojo handle.";
       return MOJO_RESULT_UNKNOWN;
     }
   }
   return MOJO_RESULT_OK;
 }
 
-mojo::AssociatedGroup* ChannelMojo::GetAssociatedGroup() {
-  DCHECK(bootstrap_);
-  return bootstrap_->GetAssociatedGroup();
-}
-
 void ChannelMojo::AddGenericAssociatedInterface(
     const std::string& name,
     const GenericAssociatedInterfaceFactory& factory) {
   base::AutoLock locker(associated_interface_lock_);
   auto result = associated_interfaces_.insert({ name, factory });
   DCHECK(result.second);
 }
 
 void ChannelMojo::GetGenericRemoteAssociatedInterface(
     const std::string& name,
     mojo::ScopedInterfaceEndpointHandle handle) {
   if (message_reader_)
     message_reader_->GetRemoteInterface(name, std::move(handle));
 }
 
 }  // namespace IPC