gpu: Add CHROMIUM_copy_image extension.

ui/gl/gl_image_memory.h

Index: ui/gl/gl_image_memory.h
diff --git a/ui/gl/gl_image_memory.h b/ui/gl/gl_image_memory.h
index 5015281ea3faaf5cc23b0f5b0d31d15d8f7d2fb2..e08fba1da83cd6b7c565b2b3451a60f39d187fee 100644
--- a/ui/gl/gl_image_memory.h
+++ b/ui/gl/gl_image_memory.h
@@ -34,6 +34,11 @@ class GL_EXPORT GLImageMemory : 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,