MD Settings: Fix subpage visibility and add appearance page tests

chrome/browser/resources/settings/appearance_page/appearance_page.js

Index: chrome/browser/resources/settings/appearance_page/appearance_page.js
diff --git a/chrome/browser/resources/settings/appearance_page/appearance_page.js b/chrome/browser/resources/settings/appearance_page/appearance_page.js
index 289e20bdbd4ebc0240bbd7e127c20579ecd8e3af..7ef07b57dc5ef4d13fb9a98ebc90f7be468bf5b4 100644
--- a/chrome/browser/resources/settings/appearance_page/appearance_page.js
+++ b/chrome/browser/resources/settings/appearance_page/appearance_page.js
@@ -33,7 +33,12 @@ Polymer({
      * Dictionary defining page visibility.
      * @type {!AppearancePageVisibility}
      */
-    pageVisibility: Object,
+    pageVisibility: {
+      type: Object,
+      value: function() {
+        return {};
+      },
+    },
 
     prefs: {
       type: Object,
@@ -144,6 +149,15 @@ Polymer({
   },
 
   /**
+   * @param {boolean|undefined} visibility
+   * @return {boolean}
+   * @private
+   */
+  showPage_: function(visibility) {
+    return visibility !== false;
+  },
+
+  /**
    * @param {number} zoom
    * @return {number} A zoom easier read by users.
    * @private
@@ -294,15 +308,6 @@ Polymer({
   },
 
   /**
-   * @param {boolean} bookmarksBarVisible if bookmarks bar option is visible.
-   * @return {string} 'first' if the argument is false or empty otherwise.
-   * @private
-   */
-  getFirst_: function(bookmarksBarVisible) {
-    return !bookmarksBarVisible ? 'first' : '';
-  },
-
-  /**
    * @see content::ZoomValuesEqual().
    * @param {number} zoom1
    * @param {number} zoom2