remove unnecessary paper-item dependency from site_details.

chrome/browser/resources/settings/site_settings/site_details.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/icons.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/iron-flex-layout/iron-flex-layout.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-icon-button/paper-icon-button.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_details_permission.html">
 <link rel="import" href="/site_settings/site_settings_behavior.html">
@@ skipping 23 matching lines @@
         </paper-button>
       </div>
     </dialog>
 
     <div class="settings-box first">
       <div class="favicon-image"
           style$="[[computeSiteIcon(site.originForDisplay)]]">
       </div>
       <div class="middle">[[site.originForDisplay]]</div>
     </div>
-    <div id="usage" hidden$="[[!storedData_]]">
-      <div class="settings-box first">
-        <h2>$i18n{siteSettingsUsage}</h2>
+    <template is="dom-if" if="[[storedData_]]">
+      <div id="usage">
+        <div class="settings-box first">
+          <h2>$i18n{siteSettingsUsage}</h2>
+        </div>
+        <div class="list-frame">
+          <div class="list-item" id="storage">
+            <div class="flex">[[storedData_]]</div>
+            <paper-icon-button icon="cr:delete"
+                on-tap="onConfirmClearStorage_"
+                alt="$i18n{siteSettingsDelete}"></paper-icon-button>
+          </div>
+        </div>
       </div>
-      <div class="list-frame">
-        <paper-item id="storage" hidden$="[[!storedData_]]">
-          <div class="flex">[[storedData_]]</div>
-          <paper-icon-button icon="cr:delete"
-              on-tap="onConfirmClearStorage_"
-              alt="$i18n{siteSettingsDelete}"></paper-icon-button>
-        </paper-item>
-      </div>
-    </div>
+    </template>
     <div class="settings-box first">
       <h2>$i18n{siteSettingsPermissions}</h2>
     </div>
     <div class="list-frame">
       <site-details-permission category="{{ContentSettingsTypes.COOKIES}}"
           icon="settings:cookie" id="cookies" label="$i18n{siteSettingsCookies}"
           site="[[site]]">
       </site-details-permission>
       <site-details-permission category="{{ContentSettingsTypes.GEOLOCATION}}"
           icon="settings:location-on" id="geolocation"
@@ skipping 47 matching lines @@
         $i18n{siteSettingsClearAndReset}
       </div>
     </div>
     <website-usage-private-api id="usageApi"
         website-data-usage="{{storedData_}}"
         website-storage-type="{{storageType_}}">
     </website-usage-private-api>
   </template>
   <script src="site_details.js"></script>
 </dom-module>