Change sampler code events phase from instant to meta.

base/trace_event/memory_dump_manager.cc

Index: base/trace_event/memory_dump_manager.cc
diff --git a/base/trace_event/memory_dump_manager.cc b/base/trace_event/memory_dump_manager.cc
index a5492028f4ec8b534369b8246503eae416ca4bbe..5c4d386698aff8ea98d158f34466b6581fa28cbc 100644
--- a/base/trace_event/memory_dump_manager.cc
+++ b/base/trace_event/memory_dump_manager.cc
@@ -546,10 +546,12 @@ void MemoryDumpManager::OnTraceLogEnabled() {
     stack_frame_deduplicator = new StackFrameDeduplicator;
     type_name_deduplicator = new TypeNameDeduplicator;
     TRACE_EVENT_API_ADD_METADATA_EVENT(
-        "stackFrames", "stackFrames",
+        TraceLog::GetCategoryGroupEnabled("__metadata"), "stackFrames",
+        "stackFrames",
         scoped_refptr<ConvertableToTraceFormat>(stack_frame_deduplicator));
     TRACE_EVENT_API_ADD_METADATA_EVENT(
-        "typeNames", "typeNames",
+        TraceLog::GetCategoryGroupEnabled("__metadata"), "typeNames",
+        "typeNames",
         scoped_refptr<ConvertableToTraceFormat>(type_name_deduplicator));
   }