When network time is unavailable, record the reason in UMA

chrome/browser/upgrade_detector_impl.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 "chrome/browser/upgrade_detector_impl.h"
 
 #include <stdint.h>
 
 #include <memory>
 #include <string>
@@ skipping 392 matching lines @@
 
 #if defined(OS_WIN)
     // Don't show the update bubbles to enterprise users (i.e., on a domain).
     if (base::win::IsEnrolledToDomain())
       return false;
 #endif
   }
 
   base::Time network_time;
   base::TimeDelta uncertainty;
-  if (!g_browser_process->network_time_tracker()->GetNetworkTime(
-          &network_time, &uncertainty)) {
+  if (g_browser_process->network_time_tracker()->GetNetworkTime(&network_time,
+                                                                &uncertainty) !=
+      network_time::NetworkTimeTracker::NETWORK_TIME_AVAILABLE) {

[Lei Zhang, 2016/08/18 16:51:19]

network time, network time, network time!

     // When network time has not been initialized yet, simply rely on the
     // machine's current time.
     network_time = base::Time::Now();
   }
 
   if (network_time.is_null() || build_date_.is_null() ||
       build_date_ > network_time) {
     NOTREACHED();
     return false;
   }
@@ skipping 89 matching lines @@
 
 // static
 UpgradeDetectorImpl* UpgradeDetectorImpl::GetInstance() {
   return base::Singleton<UpgradeDetectorImpl>::get();
 }
 
 // static
 UpgradeDetector* UpgradeDetector::GetInstance() {
   return UpgradeDetectorImpl::GetInstance();
 }