Add UMA stats to track whitelist download latency.

components/autofill/browser/autocheckout/whitelist_manager.cc

Index: components/autofill/browser/autocheckout/whitelist_manager.cc
diff --git a/components/autofill/browser/autocheckout/whitelist_manager.cc b/components/autofill/browser/autocheckout/whitelist_manager.cc
index aeb60f113393bfbe12ee93af31708c6632f2588a..85db78083b372d1af870d58bd736d6425583877c 100644
--- a/components/autofill/browser/autocheckout/whitelist_manager.cc
+++ b/components/autofill/browser/autocheckout/whitelist_manager.cc
@@ -74,9 +74,15 @@ void WhitelistManager::StartDownloadTimer(size_t interval_seconds) {
                         &WhitelistManager::TriggerDownload);
 }
 
+const AutofillMetrics& WhitelistManager::GetMetricLogger() const {
+  return metrics_logger_;
+}
+
 void WhitelistManager::TriggerDownload() {
   callback_is_pending_ = true;
 
+  request_started_timestamp_ = base::Time::Now();
+
   request_.reset(net::URLFetcher::Create(
       0, GURL(kWhitelistUrl), net::URLFetcher::GET, this));
   request_->SetRequestContext(context_getter_);
@@ -98,12 +104,20 @@ void WhitelistManager::OnURLFetchComplete(
   scoped_ptr<net::URLFetcher> old_request = request_.Pass();
   DCHECK_EQ(source, old_request.get());
 
+  AutofillMetrics::AutocheckoutWhitelistDownloadStatus status;
+  base::TimeDelta duration = base::Time::Now() - request_started_timestamp_;
+
   if (source->GetResponseCode() == net::HTTP_OK) {
     std::string data;
     source->GetResponseAsString(&data);
     BuildWhitelist(data);
+    status = AutofillMetrics::AUTOCHECKOUT_WHITELIST_DOWNLOAD_SUCCEEDED;
+  } else {
+    status = AutofillMetrics::AUTOCHECKOUT_WHITELIST_DOWNLOAD_FAILED;
   }
 
+  GetMetricLogger().LogAutocheckoutWhitelistDownloadDuration(duration, status);
+
   ScheduleDownload(kDownloadIntervalSeconds);
 }