Add UMA for estimating disk bandwidth and the time saved with parallel download

content/browser/download/download_file_impl.h

Index: content/browser/download/download_file_impl.h
diff --git a/content/browser/download/download_file_impl.h b/content/browser/download/download_file_impl.h
index 61f1f4d90bb054a524b32e402f78111c7d1de5a0..4cfe56dae7e59e5f9e6812e66b8d30b1bfe9b8d7 100644
--- a/content/browser/download/download_file_impl.h
+++ b/content/browser/download/download_file_impl.h
@@ -71,6 +71,7 @@ class CONTENT_EXPORT DownloadFileImpl : public DownloadFile {
   void Cancel() override;
   const base::FilePath& FullPath() const override;
   bool InProgress() const override;
+  void Pause() override;
 
  protected:
   // For test class overrides.
@@ -223,6 +224,13 @@ class CONTENT_EXPORT DownloadFileImpl : public DownloadFile {
   base::TimeDelta disk_writes_time_;
   base::TimeTicks download_start_;
   RateEstimator rate_estimator_;
+  int num_active_streams_;
+  bool record_stream_bandwidth_;
+  base::TimeTicks last_update_time_;
+  size_t bytes_seen_with_parallel_streams_;
+  size_t bytes_seen_without_parallel_streams_;
+  base::TimeDelta download_time_with_parallel_streams_;
+  base::TimeDelta download_time_without_parallel_streams_;
 
   std::vector<DownloadItem::ReceivedSlice> received_slices_;