Add OVERRIDE to gpu/ and gl/.

ui/gfx/gl/gl_surface_stub.h

Index: ui/gfx/gl/gl_surface_stub.h
diff --git a/ui/gfx/gl/gl_surface_stub.h b/ui/gfx/gl/gl_surface_stub.h
index 002a30030f15f628704384cf204229c270f23a64..76f36ad13fa934422fc493ed4fea0d1ec0197e50 100644
--- a/ui/gfx/gl/gl_surface_stub.h
+++ b/ui/gfx/gl/gl_surface_stub.h
@@ -18,11 +18,11 @@ class GL_EXPORT GLSurfaceStub : public GLSurface {
   void SetSize(const gfx::Size& size) { size_ = size; }
 
   // Implement GLSurface.
-  virtual void Destroy();
-  virtual bool IsOffscreen();
-  virtual bool SwapBuffers();
-  virtual gfx::Size GetSize();
-  virtual void* GetHandle();
+  virtual void Destroy() OVERRIDE;
+  virtual bool IsOffscreen() OVERRIDE;
+  virtual bool SwapBuffers() OVERRIDE;
+  virtual gfx::Size GetSize() OVERRIDE;
+  virtual void* GetHandle() OVERRIDE;
 
  private:
   gfx::Size size_;