Method beforeClosed

src/material/dialog/dialog-ref.ts:175–177

* Gets an observable that is notified when the dialog has started closing.

()

   * Gets an observable that is notified when the dialog has started closing.
   */
  beforeClosed(): Observable<R | undefined> {
    return this._beforeClosed;
  }

  /**
   * Gets an observable that emits when the overlay's backdrop has been clicked.