Removed obsolete member variable GLCanvas3D::m_color_by

src/slic3r/GUI/GLCanvas3D.hpp

@@ -522,8 +522,6 @@ private:
     // I just don't want to do it now before a release (Lukas Matena 24.3.2019)
     bool m_render_sla_auxiliaries;
 
-    std::string m_color_by;
-
     bool m_reload_delayed;
 
 #if ENABLE_RENDER_PICKING_PASS
@@ -692,8 +690,6 @@ public:
     bool                                get_use_clipping_planes() const { return m_use_clipping_planes; }
     const std::array<ClippingPlane, 2> &get_clipping_planes() const { return m_clipping_planes; };
 
-    void set_color_by(const std::string& value);
-
     void refresh_camera_scene_box();
 
     BoundingBoxf3 volumes_bounding_box() const;