_scrollHeader(scrollDir) {
        const /** @type {?} */ viewLength = this._tabListContainer.nativeElement.offsetWidth;
        // Move the scroll distance one-third the length of the tab list's viewport.
        this.scrollDistance += (scrollDir == 'before' ? -1 : 1) * viewLength / 3;
    }
/**
     * Moves the tab list in the 'before' or 'after' direction (towards the beginning of the list or
     * the end of the list, respectively). The distance to scroll is computed to be a third of the
     * length of the tab list view window.
     *
     * This is an expensive call that forces a layout reflow to compute box and scroll metrics and
     * should be called sparingly.
     * @param {?} scrollDir
     * @return {?}
     */
Moves the tab list in the 'before' or 'after' direction (towards the beginning of the list or
the end of the list, respectively). The distance to scroll is computed to be a third of the
length of the tab list view window.

This is an expensive call that forces a layout reflow to compute box and scroll metrics and
should be called sparingly.
@param {?} scrollDir
@return {?}
Moves the tab list in the ' before ' or ' after ' direction ( towards the beginning of the list or the end of the list respectively ) . The distance to scroll is computed to be a third of the length of the tab list view window . This is an expensive call that forces a layout reflow to compute box and scroll metrics and should be called sparingly . @param { ? } scrollDir @return { ? }
_scrollHeader(scrollDir) {
        const  viewLength = this._tabListContainer.nativeElement.offsetWidth;
        this.scrollDistance += (scrollDir == 'before' ? -1 : 1) * viewLength / 3;
    }
_scrollHeader ( scrollDir ) { const viewLength = this . _tabListContainer . nativeElement . offsetWidth ; this . scrollDistance += ( scrollDir == 'before' ? - 1 : 1 ) * viewLength / 3 ; }
Moves the tab list in the 'before' or 'after' direction (towards the beginning of the list or
 the end of the list, respectively).
Moves the tab list in the ' before ' or ' after ' direction ( towards the beginning of the list or the end of the list respectively ) .
/** @type {?} */ // Move the scroll distance one-third the length of the tab list's viewport.