isTextTrackVisible() {
    const expected = this.isTextVisible_;
    if (this.textDisplayer_) {
      const actual = this.textDisplayer_.isTextVisible();
      goog.asserts.assert(
          actual == expected, 'text visibility has fallen out of sync');

      // Always return the actual value so that the app has the most accurate
      // information (in the case that the values come out of sync in prod).
      return actual;
    }

    return expected;
  }
Check if the text displayer is enabled.

@return {boolean}
@export