MD Settings: Restore focus after exiting various subpages.

chrome/browser/resources/settings/printing_page/printing_page.js

 // Copyright 2016 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.
 
 Polymer({
   is: 'settings-printing-page',
 
   properties: {
     /** Preferences state. */
     prefs: {
@@ skipping 16 matching lines @@
 
     /** @type {!Array<!CupsPrinterInfo>} */
     cupsPrinters: {
       type: Array,
       notify: true,
     },
 
     searchTerm: {
       type: String,
     },
+
+    /** @private {!Map<string, string>} */
+    focusConfig_: {
+      type: Object,
+      value: function() {
+        var map = new Map();
+        map.set(
+            settings.Route.CLOUD_PRINTERS.path,
+            '#cloudPrinters .subpage-arrow');
+// <if expr="chromeos">
+        map.set(
+            settings.Route.CUPS_PRINTERS.path, '#cupsPrinters .subpage-arrow');
+// </if>
+        return map;
+      },
+    },
   },
 
   listeners: {
     'show-cups-printer-details': 'onShowCupsPrinterDetailsPage_',
   },
 
 // <if expr="chromeos">
   /** @private */
   onTapCupsPrinters_: function() {
     settings.navigateTo(settings.Route.CUPS_PRINTERS);
   },
 
   /** @private */
   onShowCupsPrinterDetailsPage_: function(event) {
     settings.navigateTo(settings.Route.CUPS_PRINTER_DETAIL);
     this.$.arraySelector.select(event.detail);
   },
 // </if>
 
   /** @private */
   onTapCloudPrinters_: function() {
     settings.navigateTo(settings.Route.CLOUD_PRINTERS);
   },
 });