MD Settings: Restore focus after exiting various subpages.

chrome/browser/resources/settings/a11y_page/a11y_page.js

Index: chrome/browser/resources/settings/a11y_page/a11y_page.js
diff --git a/chrome/browser/resources/settings/a11y_page/a11y_page.js b/chrome/browser/resources/settings/a11y_page/a11y_page.js
index be4d808a838a3515352591db4a3138d080dcaf0c..1511e106c87a8e8d165d0860ffd5d5cefac82af3 100644
--- a/chrome/browser/resources/settings/a11y_page/a11y_page.js
+++ b/chrome/browser/resources/settings/a11y_page/a11y_page.js
@@ -27,9 +27,20 @@ Polymer({
       type: Object,
       notify: true,
     },
+
+    /** @private {?Map<string, string>} */
+    focusConfig_: Object,
   },
 
 // <if expr="chromeos">
+  /** @override */
+  ready: function() {
+    this.focusConfig_ = new Map();

[Dan Beam, 2017/04/11 02:23:56]

is there a reason we can't just set

this.$.pages.focusConfig = new Map();

here instead of using binding?  OR

focusConfig_: {
  type: Object,
  value: function() {
    var focusConfig = new Map();
    focusConfig.set(..., ...);
    return focusConfig;
  },
},

to fully use properties?

[dpapad, 2017/04/11 03:01:01]

Done. It was a remainder from my original approach which was calling
querySelector() in ready(), not needed anymore.

+    this.focusConfig_.set(
+        settings.Route.MANAGE_ACCESSIBILITY.path,
+        '#subpage-trigger .subpage-arrow');
+  },
+
   /** @private */
   onManageAccessibilityFeaturesTap_: function() {
     settings.navigateTo(settings.Route.MANAGE_ACCESSIBILITY);