[MD settings] replace secondary-action with separator

chrome/browser/resources/settings/about_page/detailed_build_info.html

 <link rel="import" href="chrome://resources/html/polymer.html">
 <link rel="import" href="about_page_browser_proxy.html">
 <link rel="import" href="channel_switcher_dialog.html">
 <link rel="import" href="../i18n_setup.html">
 <link rel="import" href="../settings_shared_css.html">
 <link rel="import" href="chrome://resources/cr_elements/policy/cr_policy_indicator.html">
 <link rel="import" href="chrome://resources/html/i18n_behavior.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-button/paper-button.html">
 
 <dom-module id="settings-detailed-build-info">
@@ skipping 21 matching lines @@
     <div class="settings-box two-line single-column"
         hidden$="[[!shouldShowVersion_(versionInfo_.osFirmware)]]">
       <div>$i18n{aboutFirmwareLabel}</div>
       <div class="secondary" id="osFirmware">[[versionInfo_.osFirmware]]</div>
     </div>
     <div class="settings-box two-line">
       <div class="start">
         <div>$i18n{aboutChannelLabel}</div>
         <div class="secondary">[[currentlyOnChannelText_]]</div>
       </div>
-      <div class="secondary-action">
-        <paper-button on-tap="onChangeChannelTap_"
-            disabled="[[!canChangeChannel_]]">
-          $i18n{aboutChangeChannel}
-        </paper-button>
-        <template is="dom-if" if="[[!canChangeChannel_]]">
-          <cr-policy-indicator
-              indicator-source-name="[[getChangeChannelIndicatorSourceName_(
-                  canChangeChannel_)]]"
-              indicator-type="[[getChangeChannelIndicatorType_(
-                  canChangeChannel_)]]">
-          </cr-policy-indicator>
-        </template>
-      </div>
+      <div class="separator"></div>
+      <paper-button on-tap="onChangeChannelTap_"
+          disabled="[[!canChangeChannel_]]">
+        $i18n{aboutChangeChannel}
+      </paper-button>
+      <template is="dom-if" if="[[!canChangeChannel_]]">
+        <cr-policy-indicator
+            indicator-source-name="[[getChangeChannelIndicatorSourceName_(
+                canChangeChannel_)]]"
+            indicator-type="[[getChangeChannelIndicatorType_(
+                canChangeChannel_)]]">
+        </cr-policy-indicator>
+      </template>
       <template is="dom-if" if="[[showChannelSwitcherDialog_]]" restamp>
         <settings-channel-switcher-dialog
             on-close="onChannelSwitcherDialogClosed_">
         </settings-channel-switcher-dialog>
       </template>
     </div>
     <div class="settings-box two-line single-column"
         hidden$="[[!shouldShowVersion_(versionInfo_.arcVersion)]]">
       <div>$i18n{aboutArcVersionLabel}</div>
       <div class="secondary" id="arcVersion">[[versionInfo_.arcVersion]]</div>
@@ skipping 14 matching lines @@
       <div>$i18n{aboutCommandLineLabel}</div>
       <div id="command-line" class="secondary">$i18n{aboutCommandLine}</div>
     </div>
     <div class="settings-box two-line single-column">
       <div>$i18n{aboutBuildDateLabel}</div>
       <div class="secondary">$i18n{aboutBuildDate}</div>
     </div>
   </template>
   <script src="detailed_build_info.js"></script>
 </dom-module>