Change base::TickClock to a ref counted class.

components/network_time/network_time_tracker.cc

Index: components/network_time/network_time_tracker.cc
diff --git a/components/network_time/network_time_tracker.cc b/components/network_time/network_time_tracker.cc
index 76ee415555c4a9d2e0efabd621c4bf627b848d26..f6eb4d40392105a5fc5c0e69eb5e07311502ba88 100644
--- a/components/network_time/network_time_tracker.cc
+++ b/components/network_time/network_time_tracker.cc
@@ -35,9 +35,10 @@ void NetworkTimeTracker::RegisterPrefs(PrefRegistrySimple* registry) {
                                    new base::DictionaryValue());
 }
 
-NetworkTimeTracker::NetworkTimeTracker(scoped_ptr<base::TickClock> tick_clock,
-                                       PrefService* pref_service)
-    : tick_clock_(tick_clock.Pass()),
+NetworkTimeTracker::NetworkTimeTracker(
+    const scoped_refptr<base::TickClock>& tick_clock,
+    PrefService* pref_service)
+    : tick_clock_(tick_clock),
       pref_service_(pref_service),
       received_network_time_(false) {
   const base::DictionaryValue* time_mapping =