MD Settings: fix aria-label of Content/Site Setting subpage arrow

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/policy/cr_policy_vars_css.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/iron-flex-layout/iron-flex-layout-classes.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">
 <link rel="import" href="../clear_browsing_data_dialog/clear_browsing_data_dialog.html">
 <link rel="import" href="../controls/settings_toggle_button.html">
@@ skipping 150 matching lines @@
         <div id="site-settings-subpage-trigger"
             class="settings-box two-line" actionable
             on-tap="onSiteSettingsTap_">
           <div class="start">
             [[siteSettingsPageTitle_()]]
             <div class="secondary" id="siteSettingsSecondary">
               $i18n{siteSettingsDescription}
             </div>
           </div>
           <button class="subpage-arrow" is="paper-icon-button-light"
-              aria-label="[[siteSettingsPageTitle_()]]"
+              aria-label$="[[siteSettingsPageTitle_()]]"
               aria-describedby="siteSettingsSecondary"></button>
         </div>
         <div class="settings-box two-line" id="clearBrowsingData"
             on-tap="onClearBrowsingDataTap_" actionable>
           <div class="start">
             $i18n{clearBrowsingData}
             <div class="secondary" id="clearBrowsingDataSecondary">
               $i18n{clearBrowsingDataDescription}
             </div>
           </div>
@@ skipping 271 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>