tracing: Make ConvertableToTraceFormat move-only scoped_ptr

cc/layers/layer_impl.cc

Index: cc/layers/layer_impl.cc
diff --git a/cc/layers/layer_impl.cc b/cc/layers/layer_impl.cc
index aa34a8d3a715f9adaddfe1d26ed702515f60423a..21cdbe59395592de6be2dd8509a316ea133d2fb5 100644
--- a/cc/layers/layer_impl.cc
+++ b/cc/layers/layer_impl.cc
@@ -203,8 +203,8 @@ void LayerImpl::SetScrollParent(LayerImpl* parent) {
 }
 
 void LayerImpl::SetDebugInfo(
-    scoped_refptr<base::trace_event::ConvertableToTraceFormat> other) {
-  debug_info_ = other;
+    scoped_ptr<base::trace_event::ConvertableToTraceFormat> other) {
+  debug_info_ = std::move(other);
   SetNeedsPushProperties();
 }
 
@@ -609,7 +609,7 @@ void LayerImpl::PushPropertiesTo(LayerImpl* layer) {
   update_rect_.Union(layer->update_rect());
   layer->SetUpdateRect(update_rect_);
 
-  layer->SetDebugInfo(debug_info_);
+  layer->SetDebugInfo(std::move(debug_info_));

[danakj, 2016/02/25 23:10:07]

For future archeologists. I don't see us tracing this info on the pending tree
ever currently, and if we only trace it for layers that have something novel
from the active tree that is probably okay too.

If it ends up being some serious problem, we could have the pending tree trace
its active twin's debug_info_ also.

 
   if (frame_timing_requests_dirty_) {
     layer->SetFrameTimingRequests(frame_timing_requests_);