Add DPI option selection to Print Preview.

chrome/browser/resources/print_preview/settings/dpi_settings.js

+// Copyright 2014 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.
+
+cr.define('print_preview', function() {
+  'use strict';
+
+  /**
+   * Encapsulates all settings and logic related to the DPI selection UI.
+   * @param {!print_preview.ticket_items.Dpi} ticketItem Used to read and write
+   *     the DPI ticket item.
+   * @constructor
+   * @extends {print_preview.SettingsSectionSelect}
+   */
+  function DpiSettings(ticketItem) {
+    print_preview.SettingsSectionSelect.call(this, ticketItem);
+  };
+
+  DpiSettings.prototype = {
+    __proto__: print_preview.SettingsSectionSelect.prototype,
+
+    /** @override */
+    getDefaultDisplayName_: function(option) {
+      return loadTimeData.getStringF('dpiItemLabel', option.horizontal_dpi);
+    }
+  };
+
+  // Export
+  return {
+    DpiSettings: DpiSettings
+  };
+});