feat(toolbar-buttons): Add event for notify overwritten toolbar buttons

react/features/toolbox/components/web/ToggleCameraButton.js

@@ -41,7 +41,15 @@ class ToggleCameraButton extends AbstractButton<Props, any> {
      * @returns {void}
      */
     _handleClick() {
-        this.props.dispatch(toggleCamera());
+        const { dispatch, handleClick } = this.props;
+
+        if (handleClick) {
+            handleClick();
+
+            return;
+        }
+
+        dispatch(toggleCamera());
     }
 
     /**