virtual void OnProgressEventRaised(const std::vector<int>& host_ids,
const GURL& url,
int num_total,
int num_complete) OVERRIDE;
virtual void OnErrorEventRaised(const std::vector<int>& host_ids,
virtual void OnProgressEventRaised(const std::vector<int>& host_ids,
const GURL& url,
int num_total,
int num_complete) OVERRIDE;
virtual void OnErrorEventRaised(const std::vector<int>& host_ids,