Reland of Revert of gpu: introduce glCopySubTextureCHROMIUM (patchset #1 id:1 of https://codereview…

ui/gl/gl_image.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_H_
 #define UI_GL_GL_IMAGE_H_
 
 #include "base/memory/ref_counted.h"
 #include "ui/gfx/geometry/rect.h"
 #include "ui/gfx/geometry/rect_f.h"
@@ skipping 15 matching lines @@
 
   // Get the size of the image.
   virtual gfx::Size GetSize() = 0;
 
   // Bind image to texture currently bound to |target|.
   virtual bool BindTexImage(unsigned target) = 0;
 
   // Release image from texture currently bound to |target|.
   virtual void ReleaseTexImage(unsigned target) = 0;
 
-  // Copy image to texture currently bound to |target|.
-  virtual bool CopyTexImage(unsigned target) = 0;
+  // Copy subimage to texture currently bound to |target|.
+  virtual bool CopyTexSubImage(unsigned target, int xoffset, int yoffset) = 0;

[reveman, 2015/03/04 20:56:46]

We don't really need xoffset and yoffset for this optimization. Can we just keep
this as it is and not call this function if offsets are non-zero?

[dshwang, 2015/03/04 21:02:15]

Indeed. However, implementation can handle offsets.
Anyway as you want, I'll rollback this change to as-is

 
   // Called before the texture is used for drawing.
   virtual void WillUseTexImage() = 0;
 
   // Called after the texture has been used for drawing.
   virtual void DidUseTexImage() = 0;
 
   // Called before the texture image data will be modified.
   virtual void WillModifyTexImage() = 0;
 
@@ skipping 12 matching lines @@
 
  private:
   friend class base::RefCounted<GLImage>;
 
   DISALLOW_COPY_AND_ASSIGN(GLImage);
 };
 
 }  // namespace gfx
 
 #endif  // UI_GL_GL_IMAGE_H_