Change base::TickClock to a ref counted class.

media/cast/cast_environment.h

Index: media/cast/cast_environment.h
diff --git a/media/cast/cast_environment.h b/media/cast/cast_environment.h
index d3c9474fa3f54eff7704699d79715dbf57a3c53c..b8be6b7cd8250346c15fdb8070d3b2a4d5e7753f 100644
--- a/media/cast/cast_environment.h
+++ b/media/cast/cast_environment.h
@@ -32,14 +32,14 @@ class CastEnvironment : public base::RefCountedThreadSafe<CastEnvironment> {
   };
 
   CastEnvironment(
-      scoped_ptr<base::TickClock> clock,
+      scoped_refptr<base::TickClock> clock,
       scoped_refptr<base::SingleThreadTaskRunner> main_thread_proxy,
       scoped_refptr<base::SingleThreadTaskRunner> audio_thread_proxy,
       scoped_refptr<base::SingleThreadTaskRunner> video_thread_proxy);
 
   // These are the same methods in message_loop.h, but are guaranteed to either
   // get posted to the MessageLoop if it's still alive, or be deleted otherwise.
-  // They return true iff the thread existed and the task was posted.  Note that
+  // They return true if the thread existed and the task was posted.  Note that
   // even if the task is posted, there's no guarantee that it will run, since
   // the target thread may already have a Quit message in its queue.
   bool PostTask(ThreadId identifier,
@@ -75,7 +75,7 @@ class CastEnvironment : public base::RefCountedThreadSafe<CastEnvironment> {
   scoped_refptr<base::SingleThreadTaskRunner> main_thread_proxy_;
   scoped_refptr<base::SingleThreadTaskRunner> audio_thread_proxy_;
   scoped_refptr<base::SingleThreadTaskRunner> video_thread_proxy_;
-  scoped_ptr<base::TickClock> clock_;
+  scoped_refptr<base::TickClock> clock_;
   scoped_ptr<LoggingImpl> logging_;
 
  private: