Add OVERRIDE to gpu/ and gl/.

ui/gfx/gl/gl_context_stub.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 UI_GFX_GL_GL_CONTEXT_STUB_H_
 #define UI_GFX_GL_GL_CONTEXT_STUB_H_
 #pragma once
 
 #include "ui/gfx/gl/gl_context.h"
 
 namespace gfx {
 
 // A GLContext that does nothing for unit tests.
 class GL_EXPORT GLContextStub : public GLContext {
  public:
   GLContextStub();
   virtual ~GLContextStub();
 
   // Implement GLContext.
   virtual bool Initialize(
-      GLSurface* compatible_surface, GpuPreference gpu_preference);
-  virtual void Destroy();
-  virtual bool MakeCurrent(GLSurface* surface);
-  virtual void ReleaseCurrent(GLSurface* surface);
-  virtual bool IsCurrent(GLSurface* surface);
-  virtual void* GetHandle();
-  virtual void SetSwapInterval(int interval);
-  virtual std::string GetExtensions();
+      GLSurface* compatible_surface, GpuPreference gpu_preference) OVERRIDE;
+  virtual void Destroy() OVERRIDE;
+  virtual bool MakeCurrent(GLSurface* surface) OVERRIDE;
+  virtual void ReleaseCurrent(GLSurface* surface) OVERRIDE;
+  virtual bool IsCurrent(GLSurface* surface) OVERRIDE;
+  virtual void* GetHandle() OVERRIDE;
+  virtual void SetSwapInterval(int interval) OVERRIDE;
+  virtual std::string GetExtensions() OVERRIDE;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(GLContextStub);
 };
 
 }  // namespace gfx
 
 #endif  // UI_GFX_GL_GL_CONTEXT_STUB_H_