For readability.

base/i18n/number_formatting.cc

Index: base/i18n/number_formatting.cc
diff --git a/base/i18n/number_formatting.cc b/base/i18n/number_formatting.cc
index 246425e0f401694450d180427affdba894aa4868..35ff08d76f36e86ba8b5419c916b816921fad190 100644
--- a/base/i18n/number_formatting.cc
+++ b/base/i18n/number_formatting.cc
@@ -1,4 +1,4 @@
-// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
@@ -18,6 +18,8 @@ namespace base {
 
 namespace {
 
+// A simple wrapper around icu::NumberFormat that allows for resetting it
+// (as LazyInstance does not).
 struct NumberFormatWrapper {
   NumberFormatWrapper() {
     Reset();