Move Singleton and related structs to namespace base

chrome/test/base/tracing.cc

Index: chrome/test/base/tracing.cc
diff --git a/chrome/test/base/tracing.cc b/chrome/test/base/tracing.cc
index c3280ce147ee7ef2807eb771497c1bc345a21fae..83cbbcce575d319b5ffe4a882f798076541d3e0c 100644
--- a/chrome/test/base/tracing.cc
+++ b/chrome/test/base/tracing.cc
@@ -46,7 +46,7 @@ class StringTraceSink : public content::TracingController::TraceDataSink {
 class InProcessTraceController {
  public:
   static InProcessTraceController* GetInstance() {
-    return Singleton<InProcessTraceController>::get();
+    return base::Singleton<InProcessTraceController>::get();
   }
 
   InProcessTraceController()
@@ -126,7 +126,7 @@ class InProcessTraceController {
   }
 
  private:
-  friend struct DefaultSingletonTraits<InProcessTraceController>;
+  friend struct base::DefaultSingletonTraits<InProcessTraceController>;
 
   void OnEnableTracingComplete() {
     message_loop_runner_->Quit();