Add a ConvertableToTraceFormat type to the trace framework.

content/renderer/render_thread_impl.cc

Index: content/renderer/render_thread_impl.cc
diff --git a/content/renderer/render_thread_impl.cc b/content/renderer/render_thread_impl.cc
index c35a2c5cd50c15e2aca9e25b060d48699afb2d0f..2e29aedb920cae5123d104649f01ff056289abc0 100644
--- a/content/renderer/render_thread_impl.cc
+++ b/content/renderer/render_thread_impl.cc
@@ -221,7 +221,8 @@ void AddTraceEvent(char phase,
                    const unsigned long long* arg_values,
                    unsigned char flags) {
   TRACE_EVENT_API_ADD_TRACE_EVENT(phase, category_enabled, name, id, num_args,
-                                  arg_names, arg_types, arg_values, flags);
+                                  arg_names, arg_types, arg_values, NULL,
+                                  flags);
 }
 #endif