base/threading: measure event wait times

base/threading/thread.cc

Index: base/threading/thread.cc
diff --git a/base/threading/thread.cc b/base/threading/thread.cc
index 900b1a5c6eef178ffc23a49864db92b634074952..f7d938c8483ffcb540b652e7a4d230c14708c452 100644
--- a/base/threading/thread.cc
+++ b/base/threading/thread.cc
@@ -7,6 +7,7 @@
 #include "base/bind.h"
 #include "base/lazy_instance.h"
 #include "base/location.h"
+#include "base/profiler/scoped_tracker.h"
 #include "base/synchronization/waitable_event.h"
 #include "base/third_party/dynamic_annotations/dynamic_annotations.h"
 #include "base/threading/thread_id_name_manager.h"
@@ -179,6 +180,10 @@ void Thread::StopSoon() {
 PlatformThreadId Thread::GetThreadId() const {
   // If the thread is created but not started yet, wait for |id_| being ready.
   base::ThreadRestrictions::ScopedAllowWait allow_wait;
+  // TODO(toyoshim): Remove this after a few days (crbug.com/495097)
+  tracked_objects::ScopedTracker tracking_profile(
+      FROM_HERE_WITH_EXPLICIT_FUNCTION(
+          "495097 base::Thread::GetThreadId"));
   id_event_.Wait();
   return id_;
 }