Change sampler code events phase from instant to meta.

base/trace_event/trace_log.h

Index: base/trace_event/trace_log.h
diff --git a/base/trace_event/trace_log.h b/base/trace_event/trace_log.h
index 7d2d748df5bec240f20ecebe3bab6726e72b0079..fac7c1b12e844ce643b44e80ea5e2b9897f686f2 100644
--- a/base/trace_event/trace_log.h
+++ b/base/trace_event/trace_log.h
@@ -251,6 +251,16 @@ class BASE_EXPORT TraceLog : public MemoryDumpProvider {
 
   // Adds a metadata event that will be written when the trace log is flushed.
   void AddMetadataEvent(
+      const unsigned char* category_group_enabled,
+      const char* name,
+      int num_args,
+      const char** arg_names,
+      const unsigned char* arg_types,
+      const unsigned long long* arg_values,
+      const scoped_refptr<ConvertableToTraceFormat>* convertable_values,
+      unsigned int flags);
+
+  void AddMetadataEvent(
       const char* name,
       int num_args,
       const char** arg_names,