Add a user pref in Settings to disable all GPU features.

content/public/browser/gpu_data_manager.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_PUBLIC_BROWSER_GPU_DATA_MANAGER_H_
 #define CONTENT_PUBLIC_BROWSER_GPU_DATA_MANAGER_H_
 
 #include <list>
 #include <string>
 
@@ skipping 78 matching lines @@
   // decision.
   virtual void SetGLStrings(const std::string& gl_vendor,
                             const std::string& gl_renderer,
                             const std::string& gl_version) = 0;
 
   // Obtain collected GL strings.
   virtual void GetGLStrings(std::string* gl_vendor,
                             std::string* gl_renderer,
                             std::string* gl_version) = 0;
 
+  // Turn off all hardware acceleration.
+  virtual void DisableHardwareAcceleration() = 0;
+
  protected:
   virtual ~GpuDataManager() {}
 };
 
 };  // namespace content
 
 #endif  // CONTENT_PUBLIC_BROWSER_GPU_DATA_MANAGER_H_