Method _watchDrawerToggle

src/material/sidenav/drawer.ts:964–975

* Subscribes to drawer events in order to set a class on the main container element when the * drawer is open and the backdrop is visible. This ensures any overflow on the container element * is properly hidden.

(drawer: MatDrawer)

   * is properly hidden.
   */
  private _watchDrawerToggle(drawer: MatDrawer): void {
    drawer._animationStarted.pipe(takeUntil(this._drawers.changes)).subscribe(() => {
      this.updateContentMargins();
      this._changeDetectorRef.markForCheck();
    });

    if (drawer.mode !== 'side') {
      drawer.openedChange
        .pipe(takeUntil(this._drawers.changes))
        .subscribe(() => this._setContainerClass(drawer.opened));
    }
  }

  /**
   * Subscribes to drawer onPositionChanged event in order to