Use TimeTicks::Now() instead of Time::Now() in upgrade detector.

chrome/browser/upgrade_detector_impl.h

 // Copyright (c) 2011 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.
 
 #ifndef CHROME_BROWSER_UPGRADE_DETECTOR_IMPL_H_
 #define CHROME_BROWSER_UPGRADE_DETECTOR_IMPL_H_
 
 #include "base/memory/weak_ptr.h"
 #include "base/timer/timer.h"
 #include "base/version.h"
@@ skipping 74 matching lines @@
   base::WeakPtrFactory<UpgradeDetectorImpl> weak_factory_;
 
   // True if this build is a dev or canary channel build.
   bool is_unstable_channel_;
 
   // True if auto update is turned on.
   bool is_auto_update_enabled_;
 
   // When the upgrade was detected - either a software update or a variations
   // update, whichever happened first.
-  base::Time upgrade_detected_time_;
+  base::TimeTicks upgrade_detected_time_;
 
   // The date the binaries were built.
   base::Time build_date_;
 
   DISALLOW_COPY_AND_ASSIGN(UpgradeDetectorImpl);
 };
 
 
 #endif  // CHROME_BROWSER_UPGRADE_DETECTOR_IMPL_H_