MD Settings: Fix subpage visibility and add appearance page tests

chrome/browser/resources/settings/appearance_page/appearance_page.html

Index: chrome/browser/resources/settings/appearance_page/appearance_page.html
diff --git a/chrome/browser/resources/settings/appearance_page/appearance_page.html b/chrome/browser/resources/settings/appearance_page/appearance_page.html
index fcc30552e0f7c06a18b6a4641c156b9c1bab9162..9e535db01ef08bbd9e2ff49dd858d7492ccc3b8b 100644
--- a/chrome/browser/resources/settings/appearance_page/appearance_page.html
+++ b/chrome/browser/resources/settings/appearance_page/appearance_page.html
@@ -41,9 +41,9 @@
         focus-config="[[focusConfig_]]">
       <neon-animatable route-path="default">
 <if expr="chromeos">
-        <div class="settings-box first two-line" id="wallpaperButton"
+        <div class="settings-box first two-line" id="setWallpaper"
             on-tap="openWallpaperManager_" actionable
-            hidden="[[!pageVisibility.setWallpaper]]">
+            hidden="[[!showPage_(pageVisibility.setWallpaper)]]">
           <div class="start">
             $i18n{setWallpaper}
             <div class="secondary" id="wallpaperSecondary">
@@ -54,12 +54,12 @@
               aria-label="$i18n{setWallpaper}"
               aria-describedby="wallpaperSecondary"></button>
         </div>
-        <div class="settings-box two-line"
-            hidden="[[!pageVisibility.setTheme]]">
+        <div id="setTheme" class="settings-box two-line"
+            hidden="[[!showPage_(pageVisibility.setTheme)]]">
 </if>
 <if expr="not chromeos">
-        <div class="settings-box two-line first"
-            hidden="[[!pageVisibility.setTheme]]">
+        <div id="setTheme" class="settings-box two-line first"
+            hidden="[[!showPage_(pageVisibility.setTheme)]]">
 </if>
           <a class="start two-line inherit-color no-outline" tabindex="-1"
               target="_blank" href$="[[getThemeHref_(themeUrl_)]]">
@@ -104,8 +104,8 @@
           </div>
 </if>
         </div>
-        <div class="settings-box"
-            hidden="[[!pageVisibility.homeButton]]">
+        <div id="homeButton" class="settings-box"
+            hidden="[[!showPage_(pageVisibility.homeButton)]]">
           <settings-toggle-button class="start" elide-label
               pref="{{prefs.browser.show_home_button}}"
               label="$i18n{showHomeButton}"
@@ -116,7 +116,8 @@
           </settings-toggle-button>
         </div>
         <template is="dom-if" if="[[prefs.browser.show_home_button.value]]">
-          <div class="list-frame" hidden="[[!pageVisibility.homeButton]]">
+          <div class="list-frame"
+              hidden="[[!showPage_(pageVisibility.homeButton)]]">
             <settings-radio-group pref="{{prefs.homepage_is_newtabpage}}">
               <controlled-radio-button class="list-item" name="true"
                   pref="[[prefs.homepage_is_newtabpage]]"
@@ -144,8 +145,8 @@
             </settings-radio-group>
           </div>
         </template>
-        <div class="settings-box"
-            hidden="[[!pageVisibility.bookmarksBar]]">
+        <div id="bookmarksBar" class="settings-box"
+            hidden="[[!showPage_(pageVisibility.bookmarksBar)]]">
           <settings-toggle-button class="start"
               pref="{{prefs.bookmark_bar.show_on_all_tabs}}"
               label="$i18n{showBookmarksBar}">
@@ -175,7 +176,8 @@
           <button class="subpage-arrow" is="paper-icon-button-light"
               aria-label="$i18n{customizeFonts}"></button>
         </div>
-        <div class="settings-box" hidden="[[!pageVisibility.pageZoom]]">
+        <div class="settings-box"
+            hidden="[[!showPage_(pageVisibility.pageZoom)]]">
           <div id="pageZoom" class="start">$i18n{pageZoom}</div>
           <div class="md-select-wrapper">
             <select id="zoomLevel" class="md-select" aria-labelledby="pageZoom"