Change base::TickClock to a ref counted class.

ui/events/test/event_generator.cc

Index: ui/events/test/event_generator.cc
diff --git a/ui/events/test/event_generator.cc b/ui/events/test/event_generator.cc
index ad9d597259c6e54c1372b16d766e40f28b211c88..9a81f11826112da7cd4b9b5f620a63608c2254ae 100644
--- a/ui/events/test/event_generator.cc
+++ b/ui/events/test/event_generator.cc
@@ -483,8 +483,9 @@ void EventGenerator::Dispatch(ui::Event* event) {
   DoDispatchEvent(event, async_);
 }
 
-void EventGenerator::SetTickClock(scoped_ptr<base::TickClock> tick_clock) {
-  tick_clock_ = tick_clock.Pass();
+void EventGenerator::SetTickClock(
+    const scoped_refptr<base::TickClock>& tick_clock) {
+  tick_clock_ = tick_clock;
 }
 
 base::TimeDelta EventGenerator::Now() {