tracing: Make ConvertableToTraceFormat move-only scoped_ptr

cc/trees/layer_tree_host_impl_unittest.cc

Index: cc/trees/layer_tree_host_impl_unittest.cc
diff --git a/cc/trees/layer_tree_host_impl_unittest.cc b/cc/trees/layer_tree_host_impl_unittest.cc
index d155c5b050e1fe68d4a41c633a8cf23fcfb785dd..d6b4e773b443653360399cd1a046e91461419825 100644
--- a/cc/trees/layer_tree_host_impl_unittest.cc
+++ b/cc/trees/layer_tree_host_impl_unittest.cc
@@ -7305,8 +7305,7 @@ TEST_F(LayerTreeHostImplTest, ForcedDrawToSoftwareDeviceBasicRender) {
   EXPECT_EQ(1, software_device->frames_ended_);
 
   // Call another API method that is likely to hit nullptr in this mode.
-  scoped_refptr<base::trace_event::TracedValue> state =
-      make_scoped_refptr(new base::trace_event::TracedValue());
+  auto state = make_scoped_ptr(new base::trace_event::TracedValue);
   host_impl_->ActivationStateAsValueInto(state.get());
 }