Revert of gpu: Completely remove GpuProcessHostUIShim.

content/browser/gpu/gpu_process_host.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_GPU_PROCESS_HOST_H_
 #define CONTENT_BROWSER_GPU_GPU_PROCESS_HOST_H_
 
 #include <stdint.h>
 
 #include <map>
@@ skipping 155 matching lines @@
  private:
   class ConnectionFilterImpl;
 
   static bool ValidateHost(GpuProcessHost* host);
 
   GpuProcessHost(int host_id, GpuProcessKind kind);
   ~GpuProcessHost() override;
 
   bool Init();
 
+  // Post an IPC message to the UI shim's message handler on the UI thread.
+  void RouteOnUIThread(const IPC::Message& message);
+
   // BrowserChildProcessHostDelegate implementation.
   bool OnMessageReceived(const IPC::Message& message) override;
   void OnChannelConnected(int32_t peer_pid) override;
   void OnProcessLaunched() override;
   void OnProcessLaunchFailed(int error_code) override;
   void OnProcessCrashed(int exit_code) override;
 
   // ui::mojom::GpuHost:
   void DidInitialize(const gpu::GPUInfo& gpu_info,
                      const gpu::GpuFeatureInfo& gpu_feature_info) override;
@@ skipping 111 matching lines @@
   gpu::GpuProcessHostActivityFlags activity_flags_;
 
   base::WeakPtrFactory<GpuProcessHost> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(GpuProcessHost);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_GPU_GPU_PROCESS_HOST_H_