Add a metric to record http response code for download requests.

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"
 #include "base/strings/string_util.h"
 #include "content/browser/download/download_resource_handler.h"
 #include "content/public/browser/download_interrupt_reasons.h"
 #include "net/http/http_content_disposition.h"
+#include "net/http/http_util.h"
 
 namespace content {
 
 namespace {
 
 // All possible error codes from the network module. Note that the error codes
 // are all positive (since histograms expect positive sample values).
 const int kAllInterruptReasonCodes[] = {
 #define INTERRUPT_REASON(label, value) (value),
 #include "content/public/browser/download_interrupt_reason_values.h"
@@ skipping 900 matching lines @@
     const base::Optional<ui::PageTransition>& page_transition) {
   if (!page_transition)
     return;
 
   UMA_HISTOGRAM_ENUMERATION(
       "Download.PageTransition",
       ui::PageTransitionStripQualifier(page_transition.value()),
       ui::PAGE_TRANSITION_LAST_CORE + 1);
 }
 
+void RecordDownloadHttpResponseCode(int response_code) {
+  UMA_HISTOGRAM_CUSTOM_ENUMERATION(
+      "Download.HttpResponseCode",
+      net::HttpUtil::MapStatusCodeForHistogram(response_code),
+      net::HttpUtil::GetStatusCodesForHistogram());
+}
+
 }  // namespace content