gpu: Add CopyTexImage function to GLImage API.

ui/gl/gl_image_surface_texture.cc

Index: ui/gl/gl_image_surface_texture.cc
diff --git a/ui/gl/gl_image_surface_texture.cc b/ui/gl/gl_image_surface_texture.cc
index 833e78bdc98809ebb34ca3b686c86416298da27c..78cab656379320c950831d61bc71881c47a2ddca 100644
--- a/ui/gl/gl_image_surface_texture.cc
+++ b/ui/gl/gl_image_surface_texture.cc
@@ -77,6 +77,10 @@ bool GLImageSurfaceTexture::BindTexImage(unsigned target) {
   return true;
 }
 
+bool GLImageSurfaceTexture::CopyTexImage(unsigned target) {
+  return false;
+}
+
 bool GLImageSurfaceTexture::ScheduleOverlayPlane(gfx::AcceleratedWidget widget,
                                                  int z_order,
                                                  OverlayTransform transform,