Add the metric to record percentage improvement for parallel download.

content/browser/download/download_stats.cc

 // 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.
 
 #include "content/browser/download/download_stats.h"
 
 #include "base/macros.h"
 #include "base/metrics/histogram_functions.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/metrics/sparse_histogram.h"
@@ skipping 801 matching lines @@
           "WithoutParallelRequests",
           bandwidth_without_parallel_streams);
     }
   }
 
   if (!uses_parallel_requests)
     return;
 
   base::TimeDelta time_saved;
   if (bytes_downloaded_with_parallel_streams > 0) {
+    int64_t bandwidth_with_parallel_streams = CalculateBandwidthBytesPerSecond(
+        bytes_downloaded_with_parallel_streams, time_with_parallel_streams);
     RecordBandwidthMetric(
         "Download.ParallelizableDownloadBandwidth."
         "WithParallelRequestsMultipleStreams",
-        CalculateBandwidthBytesPerSecond(bytes_downloaded_with_parallel_streams,
-                                         time_with_parallel_streams));
+        bandwidth_with_parallel_streams);
     if (bandwidth_without_parallel_streams > 0) {
       time_saved = base::TimeDelta::FromMilliseconds(
                        1000.0 * bytes_downloaded_with_parallel_streams /
                        bandwidth_without_parallel_streams) -
                    time_with_parallel_streams;
+      int bandwidth_ratio_percentage =
+          (100.0 * bandwidth_with_parallel_streams) /
+          bandwidth_without_parallel_streams;
+      UMA_HISTOGRAM_CUSTOM_COUNTS(
+          "Download.ParallelDownload.BandwidthRatioPercentage",
+          bandwidth_ratio_percentage, 0, 400, 101);
+      base::TimeDelta total_time =
+          time_with_parallel_streams + time_without_parallel_streams;
+      size_t total_size = bytes_downloaded_with_parallel_streams +
+                          bytes_downloaded_without_parallel_streams;
+      base::TimeDelta non_parallel_time = base::TimeDelta::FromSecondsD(
+          static_cast<double>(total_size) / bandwidth_without_parallel_streams);
+      int time_ratio_percentage =
+          100.0 * total_time.InSecondsF() / non_parallel_time.InSecondsF();
+      UMA_HISTOGRAM_CUSTOM_COUNTS(
+          "Download.ParallelDownload.TotalTimeRatioPercentage",
+          time_ratio_percentage, 0, 200, 101);
     }
   }
 
   int kMillisecondsPerHour =
       base::checked_cast<int>(base::Time::kMillisecondsPerSecond * 60 * 60);
   if (time_saved >= base::TimeDelta()) {
     UMA_HISTOGRAM_CUSTOM_COUNTS(
         "Download.EstimatedTimeSavedWithParallelDownload",
         time_saved.InMilliseconds(), 0, kMillisecondsPerHour, 50);
   } else {
@@ skipping 92 matching lines @@
 }
 
 void RecordDownloadHttpResponseCode(int response_code) {
   UMA_HISTOGRAM_CUSTOM_ENUMERATION(
       "Download.HttpResponseCode",
       net::HttpUtil::MapStatusCodeForHistogram(response_code),
       net::HttpUtil::GetStatusCodesForHistogram());
 }
 
 }  // namespace content