ui/base/models: Make ComboboxModel::GetItemCount() a constant function.

ui/views/examples/example_combobox_model.cc

Index: ui/views/examples/example_combobox_model.cc
diff --git a/ui/views/examples/example_combobox_model.cc b/ui/views/examples/example_combobox_model.cc
index 800b64e0223d92bc648917fb076fca7254f87f70..c1a6b39368c628ffddddc5781a62b1e8941f36cb 100644
--- a/ui/views/examples/example_combobox_model.cc
+++ b/ui/views/examples/example_combobox_model.cc
@@ -1,12 +1,10 @@
-// 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.
 
 #include "ui/views/examples/example_combobox_model.h"
 
-#include "base/stringprintf.h"
 #include "base/utf_string_conversions.h"
-#include "ui/base/models/combobox_model.h"
 
 namespace views {
 namespace examples {
@@ -18,7 +16,7 @@ ExampleComboboxModel::ExampleComboboxModel(const char** strings, int count)
 ExampleComboboxModel::~ExampleComboboxModel() {
 }
 
-int ExampleComboboxModel::GetItemCount() {
+int ExampleComboboxModel::GetItemCount() const {
   return count_;
 }