Use ForceShutdown to kill old GPU process.

content/browser/gpu/gpu_process_host.h

 // Copyright (c) 2011 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_
 #pragma once
 
 #include <map>
 #include <queue>
@@ skipping 65 matching lines @@
   void CreateViewCommandBuffer(
       gfx::PluginWindowHandle compositing_surface,
       int32 render_view_id,
       int32 renderer_id,
       const GPUCreateCommandBufferConfig& init_params,
       CreateCommandBufferCallback* callback);
 
   // Whether this GPU process is set up to use software rendering.
   bool software_rendering();
 
+  void ForceShutdown();
+
  private:
   GpuProcessHost(int host_id);
   virtual ~GpuProcessHost();
 
   bool Init();
 
   // Post an IPC message to the UI shim's message handler on the UI thread.
   void RouteOnUIThread(const IPC::Message& message);
 
   virtual void OnProcessLaunched() OVERRIDE;
@@ skipping 60 matching lines @@
 
   // Master switch for enabling/disabling GPU acceleration for the current
   // browser session. It does not change the acceleration settings for
   // existing tabs, just the future ones.
   CONTENT_EXPORT static bool gpu_enabled_;
 
   DISALLOW_COPY_AND_ASSIGN(GpuProcessHost);
 };
 
 #endif  // CONTENT_BROWSER_GPU_GPU_PROCESS_HOST_H_