gpu: Add CHROMIUM_copy_image extension.

ui/gl/gl_image_io_surface.mm

Index: ui/gl/gl_image_io_surface.mm
diff --git a/ui/gl/gl_image_io_surface.mm b/ui/gl/gl_image_io_surface.mm
index 4ee8d0c5eca02c4ee2ccfcd5b91dfe57d1fca0cb..c9c247fb48e2e5d349b435bca236ab006e6fe3c4 100644
--- a/ui/gl/gl_image_io_surface.mm
+++ b/ui/gl/gl_image_io_surface.mm
@@ -349,6 +349,14 @@ bool GLImageIOSurface::CopyTexSubImage(unsigned target,
   return false;
 }
 
+bool GLImageIOSurface::CopySubImageData(unsigned texture_id,
+                                        const gfx::Point& offset,
+                                        const gfx::Rect& rect,
+                                        GLFence* in_fence,
+                                        GLFence* out_fence) {
+  return false;
+}
+
 bool GLImageIOSurface::ScheduleOverlayPlane(gfx::AcceleratedWidget widget,
                                             int z_order,
                                             gfx::OverlayTransform transform,