Move Singleton and related structs to namespace base

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 f6c9115646314f6ca7e3e048fa1fda56148d30cd..e3331559d7e849c9768af57ed14577ac255cca50 100644
--- a/base/trace_event/trace_log.cc
+++ b/base/trace_event/trace_log.cc
@@ -39,18 +39,22 @@
 #include "base/trace_event/trace_event_win.h"
 #endif
 
+// The thread buckets for the sampling profiler.
+BASE_EXPORT TRACE_EVENT_API_ATOMIC_WORD g_trace_state[3];
+
+namespace base {
+namespace internal {
+
 class DeleteTraceLogForTesting {
  public:
   static void Delete() {
-    Singleton<base::trace_event::TraceLog,
-              LeakySingletonTraits<base::trace_event::TraceLog>>::OnExit(0);
+    Singleton<trace_event::TraceLog,
+              LeakySingletonTraits<trace_event::TraceLog>>::OnExit(0);
   }
 };
 
-// The thread buckets for the sampling profiler.
-BASE_EXPORT TRACE_EVENT_API_ATOMIC_WORD g_trace_state[3];
+}  // namespace internal
 
-namespace base {
 namespace trace_event {
 
 namespace {
@@ -1595,7 +1599,7 @@ void TraceLog::WaitSamplingEventForTesting() {
 }
 
 void TraceLog::DeleteForTesting() {
-  DeleteTraceLogForTesting::Delete();
+  internal::DeleteTraceLogForTesting::Delete();
 }
 
 TraceEvent* TraceLog::GetEventByHandle(TraceEventHandle handle) {