Change base::TickClock to a ref counted class.

content/renderer/media/render_media_log.cc

Index: content/renderer/media/render_media_log.cc
diff --git a/content/renderer/media/render_media_log.cc b/content/renderer/media/render_media_log.cc
index d20f622ec74688be3617ba693d7d4bc6726331d9..b260cbafc1e40d977210abfd14f077c7e904d6fb 100644
--- a/content/renderer/media/render_media_log.cc
+++ b/content/renderer/media/render_media_log.cc
@@ -58,8 +58,8 @@ void RenderMediaLog::AddEvent(scoped_ptr<media::MediaLogEvent> event) {
 RenderMediaLog::~RenderMediaLog() {}
 
 void RenderMediaLog::SetTickClockForTesting(
-    scoped_ptr<base::TickClock> tick_clock) {
-  tick_clock_.swap(tick_clock);
+    const scoped_refptr<base::TickClock>& tick_clock) {
+  tick_clock_ = tick_clock;
   last_ipc_send_time_ = tick_clock_->NowTicks();
 }