Remove a DCHECK in GpuChannelMessageFilter

gpu/ipc/service/gpu_channel.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 "gpu/ipc/service/gpu_channel.h"
 
 #include <utility>
 
 #if defined(OS_WIN)
 #include <windows.h>
@@ skipping 443 matching lines @@
 
 void GpuChannelMessageFilter::OnFilterAdded(IPC::Channel* channel) {
   DCHECK(!channel_);
   channel_ = channel;
   for (scoped_refptr<IPC::MessageFilter>& filter : channel_filters_) {
     filter->OnFilterAdded(channel_);
   }
 }
 
 void GpuChannelMessageFilter::OnFilterRemoved() {
-  DCHECK(channel_);
   for (scoped_refptr<IPC::MessageFilter>& filter : channel_filters_) {
     filter->OnFilterRemoved();
   }
   channel_ = nullptr;
   peer_pid_ = base::kNullProcessId;
 }
 
 void GpuChannelMessageFilter::OnChannelConnected(int32_t peer_pid) {
   DCHECK(peer_pid_ == base::kNullProcessId);
   peer_pid_ = peer_pid;
@@ skipping 582 matching lines @@
 
       return manager->gpu_memory_buffer_factory()
           ->AsImageFactory()
           ->CreateImageForGpuMemoryBuffer(handle, size, format, internalformat,
                                           client_id_, surface_handle);
     }
   }
 }
 
 }  // namespace gpu