Add UMA metric to track parallel download requests stats.

content/browser/download/download_request_core.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_request_core.h"
 
 #include <string>
 
 #include "base/bind.h"
 #include "base/callback_helpers.h"
@@ skipping 262 matching lines @@
       base::Time::Now(), request()->net_log(), std::move(save_info_)));
 
   if (result == DOWNLOAD_INTERRUPT_REASON_NONE)
     create_info->remote_address = request()->GetSocketAddress().host();
   create_info->connection_info = request()->response_info().connection_info;
   create_info->url_chain = request()->url_chain();
   create_info->referrer_url = GURL(request()->referrer());
   create_info->result = result;
   create_info->download_id = download_id_;
   create_info->offset = create_info->save_info->offset;
-  create_info->length = create_info->save_info->length;
   return create_info;
 }
 
 bool DownloadRequestCore::OnResponseStarted(
     const std::string& override_mime_type) {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
   DVLOG(20) << __func__ << "() " << DebugString();
   download_start_time_ = base::TimeTicks::Now();
 
   DownloadInterruptReason result =
@@ skipping 368 matching lines @@
     return DOWNLOAD_INTERRUPT_REASON_NONE;
   }
 
   if (http_headers.response_code() == net::HTTP_PARTIAL_CONTENT)
     return DOWNLOAD_INTERRUPT_REASON_SERVER_BAD_CONTENT;
 
   return DOWNLOAD_INTERRUPT_REASON_NONE;
 }
 
 }  // namespace content