MD Settings: Restore focus after exiting various subpages.

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

Index: chrome/browser/resources/settings/printing_page/printing_page.js
diff --git a/chrome/browser/resources/settings/printing_page/printing_page.js b/chrome/browser/resources/settings/printing_page/printing_page.js
index a58001fbe48169c3ecbfe61c6a7eef9ea6682204..eb1bb21280bfe30c741c0bd5105d5520f2ca6756 100644
--- a/chrome/browser/resources/settings/printing_page/printing_page.js
+++ b/chrome/browser/resources/settings/printing_page/printing_page.js
@@ -34,6 +34,22 @@ Polymer({
     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: {