
DataSpec.FLAG_ALLOW_CACHE_FRAGMENTATION is added to indicate to the cache when fragmentation is allowed. This flag is set for progressive requests only. To avoid breaking changes, CacheDataSink defaults to ignoring the flag (and enabling fragmentation) for now. Respecting the flag can be enabled manually. DownloaderConstructorHelper enables respecting of the flag. Issue: #4253 PiperOrigin-RevId: 229176835