ui: Add sub region copy support to GLImage::CopyTexImage.

ui/gl/gl_image_stub.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 UI_GL_GL_IMAGE_STUB_H_
 #define UI_GL_GL_IMAGE_STUB_H_
 
 #include "ui/gl/gl_image.h"
 
 namespace gfx {
 
 // A GLImage that does nothing for unit tests.
 class GL_EXPORT GLImageStub : public GLImage {
  public:
   GLImageStub();
 
   // Overridden from GLImage:
   void Destroy(bool have_context) override {}
   gfx::Size GetSize() override;
   unsigned GetInternalFormat() override;
   bool BindTexImage(unsigned target) override;
   void ReleaseTexImage(unsigned target) override {}
-  bool CopyTexImage(unsigned target) override;
+  bool CopyTexSubImage(unsigned target,
+                       const Point& offset,
+                       const Rect& rect) override;
   void WillUseTexImage() override {}
   void DidUseTexImage() override {}
   void WillModifyTexImage() override {}
   void DidModifyTexImage() override {}
   bool ScheduleOverlayPlane(gfx::AcceleratedWidget widget,
                             int z_order,
                             OverlayTransform transform,
                             const Rect& bounds_rect,
                             const RectF& crop_rect) override;
 
  protected:
   ~GLImageStub() override;
 };
 
 }  // namespace gfx
 
 #endif  // UI_GL_GL_IMAGE_STUB_H_