tracing: Make ConvertableToTraceFormat move-only scoped_ptr

cc/scheduler/scheduler_unittest.cc

Index: cc/scheduler/scheduler_unittest.cc
diff --git a/cc/scheduler/scheduler_unittest.cc b/cc/scheduler/scheduler_unittest.cc
index 8989e0450bec60e0dbf082f8979d658c462bfd86..37fa8e0a6c9b56e3503b55ec3327822d5e37a8c0 100644
--- a/cc/scheduler/scheduler_unittest.cc
+++ b/cc/scheduler/scheduler_unittest.cc
@@ -207,8 +207,7 @@ class FakeSchedulerClient : public SchedulerClient {
   BeginFrameArgs last_begin_main_frame_args_;
   base::TimeTicks posted_begin_impl_frame_deadline_;
   std::vector<const char*> actions_;
-  std::vector<scoped_refptr<base::trace_event::ConvertableToTraceFormat>>
-      states_;
+  std::vector<scoped_ptr<base::trace_event::ConvertableToTraceFormat>> states_;
   TestScheduler* scheduler_;
 };