//アセットバンドルマニフェストをキャッシュからロードして追加する
        public IEnumerator LoadCacheManifestAsync(string rootUrl, string relativeUrl, Action onComplete, Action onFailed)
        {
            string url = GetCachePath(relativeUrl);

            url = FilePathUtil.AddFileProtocol(url);
            WWWEx wwwEx = new WWWEx(url);

            wwwEx.OnUpdate   = OnDownloadingManifest;
            wwwEx.RetryCount = 0;
            wwwEx.TimeOut    = 0.1f;
            return(wwwEx.LoadAssetBundleByNameAsync <AssetBundleManifest>(
                       AssetBundleManifestName,
                       false,
                       (manifest) =>
            {
                AddAssetBundleManifest(rootUrl, manifest);
                if (onComplete != null)
                {
                    onComplete();
                }
            },
                       () =>
            {
                if (onFailed != null)
                {
                    onFailed();
                }
            }
                       ));
        }