[MD settings] flag to enable site settings All sites and Site details pages

chrome/browser/resources/settings/site_settings_page/site_settings_page.html

 <link rel="import" href="chrome://resources/html/polymer.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-icon-button/paper-icon-button-light.html">
 <link rel="import" href="/icons.html">
 <link rel="import" href="/route.html">
 <link rel="import" href="/settings_shared_css.html">
 <link rel="import" href="/site_settings/constants.html">
 <link rel="import" href="/site_settings/site_settings_behavior.html">
 <link rel="import" href="/site_settings/site_settings_prefs_browser_proxy.html">
 
 <dom-module id="settings-site-settings-page">
   <template>
     <style include="settings-shared"></style>
-    <div class="settings-box first" category$="[[ALL_SITES]]"
-        on-tap="onTapCategory" actionable>
-      <iron-icon icon="settings:list"></iron-icon>
-      <div class="middle">$i18n{siteSettingsCategoryAllSites}</div>
-      <button class="icon-arrow-right" is="paper-icon-button-light"></button>
-    </div>
-    <div class="settings-box two-line"
+    <template is="dom-if" if="[[enableSiteSettings_]]">
+      <div class="settings-box first" category$="[[ALL_SITES]]"
+          on-tap="onTapCategory" actionable>
+        <iron-icon icon="settings:list"></iron-icon>
+        <div class="middle">$i18n{siteSettingsCategoryAllSites}</div>
+        <button class="icon-arrow-right" is="paper-icon-button-light"></button>
+      </div>
+      <div class="settings-box line-only">
+      </div>
+    </template>
+    <div class="settings-box two-line first"
         category$="[[ContentSettingsTypes.COOKIES]]" on-tap="onTapCategory"
         actionable>
       <iron-icon icon="[[computeIconForContentCategory(
           ContentSettingsTypes.COOKIES)]]"></iron-icon>
       <div class="middle">
         <div>
           [[computeTitleForContentCategory(ContentSettingsTypes.COOKIES)]]
         </div>
         <div id="cookies" class="secondary"></div>
       </div>
@@ skipping 160 matching lines @@
       <iron-icon icon="[[computeIconForContentCategory(
           ContentSettingsTypes.USB_DEVICES)]]"></iron-icon>
       <div class="middle">
         [[computeTitleForContentCategory(ContentSettingsTypes.USB_DEVICES)]]
       </div>
       <button class="icon-arrow-right" is="paper-icon-button-light"></button>
     </div>
   </template>
   <script src="site_settings_page.js"></script>
 </dom-module>