getAdManager() {
    // NOTE: this clause is redundant, but it keeps the compiler from
    // inlining this function. Inlining leads to setting the adManager
    // not taking effect in the compiled build.
    // Closure has a @noinline flag, but apparently not all cases are
    // supported by it, and ours isn't.
    // If they expand support, we might be able to get rid of this
    // clause.
    if (!this.adManager_) {
      return null;
    }

    return this.adManager_;
  }
Returns a shaka.ads.AdManager instance, responsible for Dynamic
Ad Insertion functionality.

@return {shaka.extern.IAdManager}
@export