Move Singleton and related structs to namespace base

ui/events/gesture_detection/gesture_configuration_default.cc

Index: ui/events/gesture_detection/gesture_configuration_default.cc
diff --git a/ui/events/gesture_detection/gesture_configuration_default.cc b/ui/events/gesture_detection/gesture_configuration_default.cc
index 5442ad027be03f30fa84cf17b57a34325fa4aa55..b279ace49c9ebeaa64736a1efdcde73c2add29b8 100644
--- a/ui/events/gesture_detection/gesture_configuration_default.cc
+++ b/ui/events/gesture_detection/gesture_configuration_default.cc
@@ -15,13 +15,13 @@ class GestureConfigurationDefault : public GestureConfiguration {
   }
 
   static GestureConfigurationDefault* GetInstance() {
-    return Singleton<GestureConfigurationDefault>::get();
+    return base::Singleton<GestureConfigurationDefault>::get();
   }
 
  private:
   GestureConfigurationDefault() {}
 
-  friend struct DefaultSingletonTraits<GestureConfigurationDefault>;
+  friend struct base::DefaultSingletonTraits<GestureConfigurationDefault>;
   DISALLOW_COPY_AND_ASSIGN(GestureConfigurationDefault);
 };