content: Don't keep requesting the GpuChannelHost during shutdown.

content/browser/gpu/browser_gpu_channel_host_factory.h

 // 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.
 
 #ifndef CONTENT_BROWSER_GPU_BROWSER_GPU_CHANNEL_HOST_FACTORY_H_
 #define CONTENT_BROWSER_GPU_BROWSER_GPU_CHANNEL_HOST_FACTORY_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 26 matching lines @@
       size_t size) override;
 
   int GpuProcessHostId() { return gpu_host_id_; }
   gpu::GpuChannelHost* GetGpuChannel();
   int GetGpuChannelId() { return gpu_client_id_; }
 
   // Used to skip GpuChannelHost tests when there can be no GPU process.
   static bool CanUseForTesting();
 
   // Overridden from gpu::GpuChannelEstablishFactory:
+  // The factory will return a null GpuChannelHost in the callback during
+  // shutdown.
   void EstablishGpuChannel(
       const gpu::GpuChannelEstablishedCallback& callback) override;
   scoped_refptr<gpu::GpuChannelHost> EstablishGpuChannelSync() override;
 
  private:
   struct CreateRequest;
   class EstablishRequest;
 
   BrowserGpuChannelHostFactory();
   ~BrowserGpuChannelHostFactory() override;
@@ skipping 15 matching lines @@
   std::vector<gpu::GpuChannelEstablishedCallback> established_callbacks_;
 
   static BrowserGpuChannelHostFactory* instance_;
 
   DISALLOW_COPY_AND_ASSIGN(BrowserGpuChannelHostFactory);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_GPU_BROWSER_GPU_CHANNEL_HOST_FACTORY_H_