[MD settings] replace secondary-action with separator

chrome/browser/resources/settings/downloads_page/downloads_page.html

 <link rel="import" href="chrome://resources/html/util.html">
 <link rel="import" href="chrome://resources/html/polymer.html">
 <link rel="import" href="chrome://resources/html/web_ui_listener_behavior.html">
 <link rel="import" href="../controls/controlled_button.html">
 <link rel="import" href="../controls/settings_toggle_button.html">
 <link rel="import" href="../settings_shared_css.html">
 <link rel="import" href="downloads_browser_proxy.html">
 
 <dom-module id="settings-downloads-page">
   <template>
     <style include="settings-shared">
       .block {
         display: block;
       }
     </style>
     <div class="settings-box first two-line">
       <div class="start">
         <div>$i18n{downloadLocation}</div>
         <div class="secondary" no-search>
 <if expr="not chromeos">
           [[prefs.download.default_directory.value]]
 </if>
 <if expr="chromeos">
           [[getDownloadLocation_(prefs.download.default_directory.value)]]
 </if>
         </div>
       </div>
-      <div class="secondary-action">
-        <controlled-button class="secondary-button" id="changeDownloadsPath"
-            label="$i18n{changeDownloadLocation}"
-            on-tap="selectDownloadLocation_"
-            pref="[[prefs.download.default_directory]]"
-            end-justified>
-        </controlled-button>
-      </div>
+      <div class="separator"></div>
+      <controlled-button class="secondary-button" id="changeDownloadsPath"
+          label="$i18n{changeDownloadLocation}"
+          on-tap="selectDownloadLocation_"
+          pref="[[prefs.download.default_directory]]"
+          end-justified>
+      </controlled-button>
     </div>
     <div class="settings-box block">
       <settings-toggle-button
           pref="{{prefs.download.prompt_for_download}}"
           label="$i18n{promptForDownload}">
       </settings-toggle-button>
 <if expr="chromeos">
       <settings-toggle-button
           pref="{{prefs.gdata.disabled}}"
           label="$i18n{disconnectGoogleDriveAccount}"
           hidden="[[!pageVisibility.googleDrive]]">
       </settings-toggle-button>
 </if>
     </div>
     <template is="dom-if" if="[[autoOpenDownloads_]]" restamp>
       <div class="settings-box">
         <div class="start">
           $i18n{openFileTypesAutomatically}
         </div>
-        <div class="secondary-action">
-          <paper-button id="resetAutoOpenFileTypes" class="secondary-button"
-              on-tap="onClearAutoOpenFileTypesTap_">
-            $i18n{clear}
-          </paper-button>
-        </div>
+        <div class="separator"></div>
+        <paper-button id="resetAutoOpenFileTypes" class="secondary-button"
+            on-tap="onClearAutoOpenFileTypesTap_">
+          $i18n{clear}
+        </paper-button>
       </div>
     </template>
   </template>
   <script src="downloads_page.js"></script>
 </dom-module>