tracing: Make ConvertableToTraceFormat move-only scoped_ptr

cc/debug/traced_display_item_list.h

Index: cc/debug/traced_display_item_list.h
diff --git a/cc/debug/traced_display_item_list.h b/cc/debug/traced_display_item_list.h
index 6b422435c6e82f2c20d843e9f83037cd163de9dc..b06500dac95ad4ed99fda57790704045ecbd439b 100644
--- a/cc/debug/traced_display_item_list.h
+++ b/cc/debug/traced_display_item_list.h
@@ -19,10 +19,10 @@ class DisplayItemList;
 class TracedDisplayItemList
     : public base::trace_event::ConvertableToTraceFormat {
  public:
-  static scoped_refptr<ConvertableToTraceFormat> AsTraceableDisplayItemList(
+  static scoped_ptr<ConvertableToTraceFormat> AsTraceableDisplayItemList(
       scoped_refptr<const DisplayItemList> list,
       bool include_items) {
-    return scoped_refptr<ConvertableToTraceFormat>(
+    return scoped_ptr<ConvertableToTraceFormat>(
         new TracedDisplayItemList(list, include_items));
   }
   void AppendAsTraceFormat(std::string* out) const override;