Use a direct include of strings headers in ui/, part 1.

ui/app_list/test/app_list_test_model.cc

 // Copyright 2013 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/app_list/test/app_list_test_model.h"
 
-#include "base/stringprintf.h"
+#include "base/strings/stringprintf.h"
 #include "ui/app_list/app_list_item_model.h"
 
 namespace app_list {
 namespace test {
 
 void AppListTestModel::PopulateApps(int n) {
   for (int i = 0; i < n; ++i)
     AddItem(base::StringPrintf("Item %d", i));
 }
 
@@ skipping 21 matching lines @@
   apps()->Add(CreateItem(title));
 }
 
 void AppListTestModel::HighlightItemAt(int index) {
   AppListItemModel* item = apps()->GetItemAt(index);
   item->SetHighlighted(true);
 }
 
 }  // namespace test
 }  // namespace app_list