[tracing] Add trace events to key heap profiler functions.

base/trace_event/trace_log.cc

Index: base/trace_event/trace_log.cc
diff --git a/base/trace_event/trace_log.cc b/base/trace_event/trace_log.cc
index 4e8bc3252516b6bf291e78a71ecb8b51a97aaf12..ccea5f8164fd3e55c47de0d93b0da85049bfde0f 100644
--- a/base/trace_event/trace_log.cc
+++ b/base/trace_event/trace_log.cc
@@ -881,6 +881,8 @@ void TraceLog::ConvertTraceEventsToTraceFormat(
     std::unique_ptr<TraceBuffer> logged_events,
     const OutputCallback& flush_output_callback,
     const ArgumentFilterPredicate& argument_filter_predicate) {
+  TRACE_EVENT0(TRACE_DISABLED_BY_DEFAULT("memory-infra"),

[Primiano Tucci (use gerrit), 2017/07/14 14:45:04]

Hmm I am not sure about this one. In all honesty having TRACE_EVENT macros
within TraceLog itself makes me a bit worried.  can you remove this?

+               "TraceLog::ConvertTraceEventsToTraceFormat");
   if (flush_output_callback.is_null())
     return;