Move Singleton and related structs to namespace base

ui/gfx/android/shared_device_display_info.h

Index: ui/gfx/android/shared_device_display_info.h
diff --git a/ui/gfx/android/shared_device_display_info.h b/ui/gfx/android/shared_device_display_info.h
index e6983e58aa35c3cfc8af57f37e208d17df1d2bbe..0018b3719b43e11bc71f4ed4043c68127e83130d 100644
--- a/ui/gfx/android/shared_device_display_info.h
+++ b/ui/gfx/android/shared_device_display_info.h
@@ -44,7 +44,7 @@ class SharedDeviceDisplayInfo {
                     jint smallest_dip_width,
                     jint rotation_degrees);
  private:
-  friend struct DefaultSingletonTraits<SharedDeviceDisplayInfo>;
+  friend struct base::DefaultSingletonTraits<SharedDeviceDisplayInfo>;
 
   SharedDeviceDisplayInfo();
   ~SharedDeviceDisplayInfo();