Add UMA to track why a download is non-parallel when enabled parallel

content/browser/download/parallel_download_utils.cc

 // Copyright 2017 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/parallel_download_utils.h"
 
 #include "base/metrics/field_trial_params.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/time/time.h"
 #include "content/public/browser/download_save_info.h"
@@ skipping 24 matching lines @@
 
 // TODO(qinmin): replace this with a comparator operator in
 // DownloadItem::ReceivedSlice.
 bool compareReceivedSlices(const DownloadItem::ReceivedSlice& lhs,
                            const DownloadItem::ReceivedSlice& rhs) {
   return lhs.offset < rhs.offset;
 }
 
 }  // namespace
 
-bool ShouldUseParallelDownload(const DownloadCreateInfo& create_info) {
-  // To enable parallel download, following conditions need to be satisfied.
-  // 1. Accept-Ranges, Content-Length and strong validators response headers.
-  // 2. Feature |kParallelDownloading| enabled.
-  // 3. Content-Length is no less than the minimum slice size configuration.
-  // 3. HTTP/1.1 protocol, not QUIC nor HTTP/1.0.
-
-  // Etag and last modified are stored into DownloadCreateInfo in
-  // DownloadRequestCore only if the response header complies to the strong
-  // validator rule.
-  bool has_strong_validator =
-      !create_info.etag.empty() || !create_info.last_modified.empty();
-
-  return has_strong_validator && create_info.accept_range &&
-         create_info.total_bytes >= GetMinSliceSizeConfig() &&
-         create_info.connection_info ==
-             net::HttpResponseInfo::CONNECTION_INFO_HTTP1_1 &&
-         base::FeatureList::IsEnabled(features::kParallelDownloading);
-}
-
 std::vector<DownloadItem::ReceivedSlice> FindSlicesForRemainingContent(
     int64_t current_offset,
     int64_t total_length,
     int request_count,
     int64_t min_slice_size) {
   std::vector<DownloadItem::ReceivedSlice> new_slices;
 
   if (request_count > 0) {
     int64_t slice_size =
         std::max<int64_t>(total_length / request_count, min_slice_size);
@@ skipping 88 matching lines @@
 
 void DebugSlicesInfo(const DownloadItem::ReceivedSlices& slices) {
   DVLOG(1) << "Received slices size : " << slices.size();
   for (const auto& it : slices) {
     DVLOG(1) << "Slice offset = " << it.offset
              << " , received_bytes = " << it.received_bytes;
   }
 }
 
 }  // namespace content