Change base::TickClock to a ref counted class.

components/copresence/handlers/audio/audio_directive_list.h

Index: components/copresence/handlers/audio/audio_directive_list.h
diff --git a/components/copresence/handlers/audio/audio_directive_list.h b/components/copresence/handlers/audio/audio_directive_list.h
index 4934ac1e93f19dd574c49b7e3401fa1046bc7992..027d54d3dc2fe08120282cae91d7c28c7b5806c3 100644
--- a/components/copresence/handlers/audio/audio_directive_list.h
+++ b/components/copresence/handlers/audio/audio_directive_list.h
@@ -10,6 +10,7 @@
 
 #include "base/callback.h"
 #include "base/macros.h"
+#include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/time/time.h"
 
@@ -48,6 +49,8 @@ class AudioDirectiveList {
 
   scoped_ptr<AudioDirective> GetActiveDirective();
 
+  void set_clock_for_testing(const scoped_refptr<base::TickClock>& clock);
+
  private:
   // Comparator for comparing end_times on audio tokens.
   class LatestFirstComparator {
@@ -66,7 +69,7 @@ class AudioDirectiveList {
   // element. Only currently active directives will exist in this list.
   std::vector<AudioDirective> active_directives_;
 
-  scoped_ptr<base::TickClock> clock_;
+  scoped_refptr<base::TickClock> clock_;
 
   DISALLOW_COPY_AND_ASSIGN(AudioDirectiveList);
 };