Change base::TickClock to a ref counted class.

components/copresence/handlers/audio/audio_directive_handler.h

Index: components/copresence/handlers/audio/audio_directive_handler.h
diff --git a/components/copresence/handlers/audio/audio_directive_handler.h b/components/copresence/handlers/audio/audio_directive_handler.h
index 53e4d4b55113506757e8d85c2eb2d5c1f16f02d3..0515657cd33566fe1d3b88062646e87f2b1f3854 100644
--- a/components/copresence/handlers/audio/audio_directive_handler.h
+++ b/components/copresence/handlers/audio/audio_directive_handler.h
@@ -61,6 +61,9 @@ class AudioDirectiveHandler final {
     audio_manager_ = manager.Pass();
   }
 
+  void set_clock_for_testing(const scoped_refptr<base::TickClock>& clock);
+  void set_timer_for_testing(scoped_ptr<base::Timer> timer);
+
  private:
   friend class AudioDirectiveHandlerTest;
 
@@ -79,7 +82,7 @@ class AudioDirectiveHandler final {
 
   scoped_ptr<base::Timer> audio_event_timer_;
 
-  scoped_ptr<base::TickClock> clock_;
+  scoped_refptr<base::TickClock> clock_;
 
   DISALLOW_COPY_AND_ASSIGN(AudioDirectiveHandler);
 };