Add an enrolling state for consumer management section in settings page.

chrome/browser/resources/options/browser_options.html

 <div id="settings" class="page" hidden>
   <header>
     <h1 i18n-content="settingsTitle"></h1>
   </header>
   <include src="automatic_settings_reset_banner.html">
 <if expr="chromeos">
   <include src="secondary_user_banner.html">
   <section>
     <div id="network-section-header" class="section-header">
       <h3 i18n-content="sectionTitleInternet"></h3>
@@ skipping 265 matching lines @@
       </div>
     </div>
   </section>
 
   <section id="device-control-section" hidden>
     <h3 i18n-content="deviceControlTitle"></h3>
     <div id="consumer-management-section">
       <div class="settings-row">
         <span i18n-content="consumerManagementDescription"></span>
       </div>
-      <div id="consumer-management-enroll" class="settings-row">
-        <button i18n-content="consumerManagementEnrollButton"></button>
-      </div>
-      <div id="consumer-management-unenroll" class="settings-row" hidden>
-        <button i18n-content="consumerManagementUnenrollButton"></button>
+      <div class="settings-row">
+        <button id="consumer-management-button"></button>
       </div>
     </div>
   </section>
 </if>
   <section id="privacy-section">
     <h3 i18n-content="advancedSectionTitlePrivacy"></h3>
     <div>
       <div class="settings-row">
         <button id="privacyContentSettingsButton"
             i18n-content="privacyContentSettingsButton"></button>
@@ skipping 675 matching lines @@
     <button id="advanced-settings-expander" class="link-button"
         i18n-content="showAdvancedSettings">
     </button>
 <if expr="chromeos">
     <button id="version-button" class="link-button" hidden
         i18n-content="browserVersion">
     </button>
 </if>
   </footer>
 </div>