MD Settings: Fix subpage visibility and add appearance page tests

chrome/browser/resources/settings/privacy_page/privacy_page.html

 <link rel="import" href="chrome://resources/html/polymer.html">
 <link rel="import" href="chrome://resources/cr_elements/cr_dialog/cr_dialog.html">
 <link rel="import" href="chrome://resources/cr_elements/policy/cr_policy_vars_css.html">
 <link rel="import" href="chrome://resources/html/assert.html">
 <link rel="import" href="chrome://resources/html/cr/ui/focus_without_ink.html">
 <link rel="import" href="chrome://resources/html/i18n_behavior.html">
 <link rel="import" href="chrome://resources/html/web_ui_listener_behavior.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/neon-animation/neon-animatable.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-button/paper-button.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-icon-button/paper-icon-button-light.html">
@@ skipping 37 matching lines @@
       <neon-animatable route-path="default">
         <div class="settings-box first">
           <p class="privacy-explanation">$i18nRaw{improveBrowsingExperience}</p>
         </div>
         <div class="settings-box">
           <settings-toggle-button class="start"
               pref="{{prefs.alternate_error_pages.enabled}}"
               label="$i18n{linkDoctorPref}">
           </settings-toggle-button>
         </div>
-        <div class="settings-box" hidden="[[!pageVisibility.searchPrediction]]">
+        <div class="settings-box"
+            hidden="[[!showPage_(pageVisibility.searchPrediction)]]">
           <settings-toggle-button class="start"
               pref="{{prefs.search.suggest_enabled}}"
               label="$i18n{searchSuggestPref}">
           </settings-toggle-button>
         </div>
         <div class="settings-box"
-            hidden="[[!pageVisibility.networkPrediction]]">
+            hidden="[[!showPage_(pageVisibility.networkPrediction)]]">
           <settings-toggle-button class="start"
               pref="{{prefs.net.network_prediction_options}}"
               label="$i18n{networkPredictionEnabled}"
               numeric-unchecked-value="[[networkPredictionEnum_.NEVER]]">
           </settings-toggle-button>
         </div>
         <div class="settings-box">
           <settings-toggle-button class="start"
               id="safeBrowsingExtendedReportingControl"
               pref="[[safeBrowsingExtendedReportingPref_]]"
@@ skipping 416 matching lines @@
                 category="{{ContentSettingsTypes.PROTECTED_CONTENT}}">
             </category-setting-exceptions>
           </template>
 </if>
         </settings-subpage>
       </template>
     </settings-animated-pages>
   </template>
   <script src="privacy_page.js"></script>
 </dom-module>