MD Settings: remove unnecessary secondary descriptions.

chrome/browser/resources/settings/search_page/search_page.html

 <link rel="import" href="chrome://resources/html/i18n_behavior.html">
 <link rel="import" href="chrome://resources/html/md_select_css.html">
 <link rel="import" href="chrome://resources/html/polymer.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="../controls/extension_controlled_indicator.html">
 <link rel="import" href="../controls/settings_toggle_button.html">
 <link rel="import" href="../icons.html">
 <link rel="import" href="../i18n_setup.html">
@@ skipping 102 matching lines @@
               </div>
               <button class="icon-external" is="paper-icon-button-light"
                   aria-label$="[[i18n('searchOkGoogleAudioHistoryLabel',
                                       hotwordInfo_.userName)]]"
                   aria-describedby="audioHistorySecondary"></button>
             </div>
           </template>
         </template>
 
         <!-- Manage search engines -->
-        <div id="subpage-trigger" class="settings-box two-line"
+        <div id="subpage-trigger" class="settings-box"
             on-tap="onManageSearchEnginesTap_" actionable>
           <div class="start">
             $i18n{searchEnginesManage}
-            <div class="secondary" id="manageSearchEnginesSecondary">
-              $i18n{searchEnginesManageDescription}
-            </div>
           </div>
           <button class="subpage-arrow" is="paper-icon-button-light"
-              aria-label="$i18n{searchEnginesManage}"
-              aria-describedby="manageSearchEnginesSecondary"></button>
+              aria-label="$i18n{searchEnginesManage}"></button>
         </div>
       </neon-animatable>
       <template is="dom-if" route-path="/searchEngines">
         <settings-subpage
             associated-control="[[$$('#subpage-trigger')]]"
             page-title="$i18n{searchEnginesManage}">
           <settings-search-engines-page></settings-search-engines-page>
         </settings-subpage>
       </template>
     </settings-animated-pages>
   </template>
   <script src="search_page.js"></script>
 </dom-module>