Refactor GestureNavigation to eliminate code redundancy

ui/aura_extra/image_window_delegate.h

Index: ui/aura_extra/image_window_delegate.h
diff --git a/ui/aura_extra/image_window_delegate.h b/ui/aura_extra/image_window_delegate.h
index ea36cd978575f56322e1c1ec29ec48e1f3302de8..3f5a1f9ce6e9250e7ed0bcf3fbf5760c70a1c65c 100644
--- a/ui/aura_extra/image_window_delegate.h
+++ b/ui/aura_extra/image_window_delegate.h
@@ -32,6 +32,9 @@ class AURA_EXTRA_EXPORT ImageWindowDelegate : public aura::WindowDelegate {
 
   bool has_image() const { return !image_.IsEmpty(); }
 
+  // TODO this method is an overkill, store image in ONO.
+  gfx::Image Image() const { return image_; }
+
  protected:
   ~ImageWindowDelegate() override;