gpu: Add CopyTexImage function to GLImage API.

ui/gl/gl_image_glx.cc

 // 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.
 
 extern "C" {
 #include <X11/Xlib.h>
 }
 
 #include "ui/gl/gl_image_glx.h"
 
@@ skipping 172 matching lines @@
   return true;
 }
 
 void GLImageGLX::ReleaseTexImage(unsigned target) {
   DCHECK_NE(0u, glx_pixmap_);
   DCHECK_EQ(static_cast<GLenum>(GL_TEXTURE_2D), target);
 
   glXReleaseTexImageEXT(gfx::GetXDisplay(), glx_pixmap_, GLX_FRONT_LEFT_EXT);
 }
 
+bool GLImageGLX::CopyTexImage(unsigned target) {
+  return false;
+}
+
 bool GLImageGLX::ScheduleOverlayPlane(gfx::AcceleratedWidget widget,
                                       int z_order,
                                       OverlayTransform transform,
                                       const Rect& bounds_rect,
                                       const RectF& crop_rect) {
   return false;
 }
 
 }  // namespace gfx