Add OVERRIDE to gpu/ and gl/.

ui/gfx/gl/gl_surface_osmesa.h

Index: ui/gfx/gl/gl_surface_osmesa.h
diff --git a/ui/gfx/gl/gl_surface_osmesa.h b/ui/gfx/gl/gl_surface_osmesa.h
index f0a466314e2b2d02fac984f945d0aa88ba088ebd..2e0d38438d3dd72c0919330325688cb969629aaa 100644
--- a/ui/gfx/gl/gl_surface_osmesa.h
+++ b/ui/gfx/gl/gl_surface_osmesa.h
@@ -22,16 +22,16 @@ class GL_EXPORT GLSurfaceOSMesa : public GLSurface {
 
   // Resize the back buffer, preserving the old content. Does nothing if the
   // size is unchanged.
-  virtual bool Resize(const gfx::Size& new_size);
+  virtual bool Resize(const gfx::Size& new_size) OVERRIDE;
 
   // Implement GLSurface.
-  virtual bool Initialize();
-  virtual void Destroy();
-  virtual bool IsOffscreen();
-  virtual bool SwapBuffers();
-  virtual gfx::Size GetSize();
-  virtual void* GetHandle();
-  virtual unsigned GetFormat();
+  virtual bool Initialize() OVERRIDE;
+  virtual void Destroy() OVERRIDE;
+  virtual bool IsOffscreen() OVERRIDE;
+  virtual bool SwapBuffers() OVERRIDE;
+  virtual gfx::Size GetSize() OVERRIDE;
+  virtual void* GetHandle() OVERRIDE;
+  virtual unsigned GetFormat() OVERRIDE;
 
  private:
   void AllocateBuffer(const Size& size);