Make it possible to use ThreadLocalStorage::Slot as a static without

base/tracked_objects.cc

Index: base/tracked_objects.cc
diff --git a/base/tracked_objects.cc b/base/tracked_objects.cc
index 71b3bc620237731754a26a5d92b2f5d08cbf1475..e7d7bd165b6f77c517bd0ecf4d8460f4e43d1b2b 100644
--- a/base/tracked_objects.cc
+++ b/base/tracked_objects.cc
@@ -180,7 +180,7 @@ void Births::Clear() { birth_count_ = 0; }
 // do a fake initialization here (zeroing out data), and then the real in-place
 // construction happens when we call tls_index_.Initialize().
 // static
-base::ThreadLocalStorage::Slot ThreadData::tls_index_(base::LINKER_INITIALIZED);
+base::ThreadLocalStorage::StaticSlot ThreadData::tls_index_ = TLS_INITIALIZER;
 
 // static
 int ThreadData::worker_thread_data_creation_count_ = 0;