Parallel Download finch config parameters on Chrome client.

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 "content/public/browser/download_save_info.h"
+#include "content/public/common/content_features.h"
 
 namespace content {
 
+namespace {
+
+// Finch parameter key value for minimum slice size in bytes to use parallel
+// download.
+const char kMinSliceSizeFinchKey[] = "min_slice_size";
+
+// Default value for |kMinSliceSizeFinchKey|, when no parameter is specified.
+const int64_t kMinSliceSizeParallelDownload = 2097152;
+
+// Finch parameter key value for number of parallel requests in a parallel
+// download, including the original request.
+const char kParallelRequestCountFinchKey[] = "request_count";
+
+// Default value for |kParallelRequestCountFinchKey|, when no parameter is
+// specified.
+const int kParallelRequestCount = 2;
+
+}  // namespace
+
 DownloadItem::ReceivedSlice FindNextSliceToDownload(
     const std::vector<DownloadItem::ReceivedSlice>& received_slices) {
   if (received_slices.empty())
     return DownloadItem::ReceivedSlice(0, DownloadSaveInfo::kLengthFullContent);
 
   std::vector<DownloadItem::ReceivedSlice>::const_iterator iter =
       received_slices.begin();
   DCHECK_GE(iter->offset, 0);
   if (iter->offset != 0)
     return DownloadItem::ReceivedSlice(0, iter->offset);
@@ skipping 10 matching lines @@
     DCHECK_GE(next->offset, offset);
     if (next->offset > offset) {
       remaining_bytes = next->offset - offset;
       break;
     }
     iter = next;
   }
   return DownloadItem::ReceivedSlice(offset, remaining_bytes);
 }
 
+int64_t GetMinSliceSizeConfig() {
+  std::string finch_value = base::GetFieldTrialParamValueByFeature(
+      features::kParallelDownloading, kMinSliceSizeFinchKey);
+  int64_t result;
+  return !finch_value.empty() && base::StringToInt64(finch_value, &result)
+             ? result
+             : kMinSliceSizeParallelDownload;
+}
+
+int GetParallelRequestCountConfig() {
+  std::string finch_value = base::GetFieldTrialParamValueByFeature(
+      features::kParallelDownloading, kParallelRequestCountFinchKey);
+  int result;
+  return !finch_value.empty() && base::StringToInt(finch_value, &result)
+             ? result
+             : kParallelRequestCount;
+}
+
 }  // namespace content