[Passwords] Add focusConfig for Password Check button

This change adds a focusConfig for the Password Check button to
passwords_section.js, allowing for the proper highlighting when
navigating from chrome://settings/passwords/check to
chrome://settings/passwords.

Since the Password Check button is not an immediate child of the parent
autofill page, but rather embedded within the passwords section, a
single query selector string is not sufficient, and executing our own
handler is required.

Fixed: 1101298
Change-Id: I76a23778461880e38f23a25f2b9f4d2ca5328dae
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2275455
Commit-Queue: Jan Wilken Dörrie <jdoerrie@chromium.org>
Reviewed-by: dpapad <dpapad@chromium.org>
Cr-Commit-Position: refs/heads/master@{#785952}

chrome/browser/resources/settings/autofill_page/autofill_page.html

@@ -33,7 +33,7 @@
             search-label="$i18n{searchPasswords}"
             search-term="{{passwordFilter_}}">
           <passwords-section id="passwordSection" filter="[[passwordFilter_]]"
-              prefs="{{prefs}}">
+              focus-config="[[focusConfig_]]" prefs="{{prefs}}">
           </passwords-section>
         </settings-subpage>
       </template>

chrome/browser/resources/settings/autofill_page/passwords_section.html

@@ -133,7 +133,7 @@
             $i18n{checkPasswordsDescription}
           </div>
         </div>
-        <cr-icon-button class="subpage-arrow"
+        <cr-icon-button id="icon" class="subpage-arrow"
             aria-label="$i18n{checkPasswords}">
         </cr-icon-button>
       </div>

chrome/browser/resources/settings/autofill_page/passwords_section.js

@@ -95,6 +95,12 @@ Polymer({
     storedAccounts_: Array,
     // </if>
 
+    /** @type {!Map<string, (string|Function)>} */
+    focusConfig: {
+      type: Object,
+      observer: 'focusConfigChanged_',
+    },
+
     /** Preferences state. */
     prefs: {
       type: Object,
@@ -308,6 +314,26 @@ Polymer({
    */
   setPasswordExceptionsListener_: null,
 
+  /**
+   * @param {!Map<string, string>} newConfig
+   * @param {?Map<string, string>} oldConfig
+   * @private
+   */
+  focusConfigChanged_(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-autofill-page>
+    // element, with additional entries that correspond to subpage trigger
+    // elements residing in this element's Shadow DOM.
+    if (this.enablePasswordCheck_) {
+      this.focusConfig.set(assert(routes.CHECK_PASSWORDS).path, () => {
+        focusWithoutInk(assert(this.$$('#icon')));
+      });
+    }
+  },
+
   /** @override */
   attached() {
     // Create listener functions.