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

content/browser/download/download_file_impl.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CONTENT_BROWSER_DOWNLOAD_DOWNLOAD_FILE_IMPL_H_
 #define CONTENT_BROWSER_DOWNLOAD_DOWNLOAD_FILE_IMPL_H_
 
 #include "content/browser/download/download_file.h"
 
 #include <stddef.h>
@@ skipping 53 matching lines @@
                          const RenameCompletionCallback& callback) override;
   void RenameAndAnnotate(const base::FilePath& full_path,
                          const std::string& client_guid,
                          const GURL& source_url,
                          const GURL& referrer_url,
                          const RenameCompletionCallback& callback) override;
   void Detach() override;
   void Cancel() override;
   const base::FilePath& FullPath() const override;
   bool InProgress() const override;
+  void Pause() override;
 
  protected:
   // For test class overrides.
   // Write data from the offset to the file.
   // On OS level, it will seek to the |offset| and write from there.
   virtual DownloadInterruptReason WriteDataToFile(int64_t offset,
                                                   const char* data,
                                                   size_t data_len);
 
   virtual base::TimeDelta GetRetryDelayForFailedRename(int attempt_number);
@@ skipping 132 matching lines @@
   // Set to true when multiple byte streams write to the same file.
   // The file may contain null bytes(holes) in between of valid data slices.
   // TODO(xingliu): Pass a slice info vector to determine if the file is sparse.
   bool is_sparse_file_;
 
   // Statistics
   size_t bytes_seen_;
   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_;
 
   base::WeakPtr<DownloadDestinationObserver> observer_;
   base::WeakPtrFactory<DownloadFileImpl> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(DownloadFileImpl);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_DOWNLOAD_DOWNLOAD_FILE_IMPL_H_