MD Settings: Focus cookies search field when exiting cookie details subpage.

chrome/browser/resources/settings/site_settings/site_data.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.
 
 /**
  * @fileoverview
  * 'site-data' handles showing the local storage summary list for all sites.
  */
 
 /**
@@ skipping 16 matching lines @@
      * The current filter applied to the cookie data list.
      * @private
      */
     filterString_: {
       type: String,
       value: '',
     },
 
     /** @private */
     confirmationDeleteMsg_: String,
+
+    /** @type {!Map<string, string>} */
+    focusConfig: {
+      type: Object,
+      observer: 'focusConfigChanged_',
+    },
+  },
+
+  /**
+   * @param {!Map<string, string>} newConfig
+   * @param {?Map<string, string>} oldConfig
+   * @private
+   */
+  focusConfigChanged_: function(newConfig, oldConfig) {
+    // focusConfig is set only once on the parent, so this observer should only
+    // fire once.
+    assert(!oldConfig);
+
+    // Populate the |focusConfig| map of the parent <settings-animated-pages>
+    // element, with additional entries that correspond to subpage trigger
+    // elements residing in this element's Shadow DOM.
+    this.focusConfig.set(
+        settings.Route.SITE_SETTINGS_DATA_DETAILS.path,
+        '* /deep/ #filter /deep/ #searchInput');
   },
 
   /** @override */
   ready: function() {
     this.loadCookies();
   },
 
   /**
    * A filter function for the list.
    * @param {!CookieDataSummaryItem} item The item to possibly filter out.
@@ skipping 85 matching lines @@
 
   /**
    * @param {!{model: !{item: CookieDataSummaryItem}}} event
    * @private
    */
   onSiteTap_: function(event) {
     settings.navigateTo(settings.Route.SITE_SETTINGS_DATA_DETAILS,
         new URLSearchParams('site=' + event.model.item.site));
   },
 });