gpu: Add CHROMIUM_copy_image extension.

ui/gl/gl_image_io_surface.h

Index: ui/gl/gl_image_io_surface.h
diff --git a/ui/gl/gl_image_io_surface.h b/ui/gl/gl_image_io_surface.h
index a78bcc16a3737a0190e4fde8c3986860c140f3a7..eb523aa2b323b57cc61a3e2960af46a4db94b3af 100644
--- a/ui/gl/gl_image_io_surface.h
+++ b/ui/gl/gl_image_io_surface.h
@@ -51,6 +51,11 @@ class GL_EXPORT GLImageIOSurface : public GLImage {
   bool CopyTexSubImage(unsigned target,
                        const gfx::Point& offset,
                        const gfx::Rect& rect) override;
+  bool CopySubImageData(unsigned texture_id,
+                        const gfx::Point& offset,
+                        const gfx::Rect& rect,
+                        GLFence* in_fence,
+                        GLFence* out_fence) override;
   bool ScheduleOverlayPlane(gfx::AcceleratedWidget widget,
                             int z_order,
                             gfx::OverlayTransform transform,