Fine tuned availability of hotword plugin.

chrome/browser/resources/options/browser_options.html

 <div id="settings" class="page" hidden>
   <header>
     <h1 i18n-content="settingsTitle"></h1>
   </header>
   <include src="reset_profile_settings_banner.html">
   <include src="automatic_settings_reset_banner.html">
 <if expr="not pp_ifdef('chromeos')">
   <include src="sync_section.html">
 </if>
 <if expr="pp_ifdef('chromeos')">
@@ skipping 334 matching lines @@
             </label>
             <a target="_blank" i18n-content="learnMore"
                 i18n-values="href:contentProtectionAttestationLearnMoreURL">
             </a>
             <span class="controlled-setting-indicator"
                 pref="cros.device.attestation_for_content_protection_enabled">
             </span>
           </span>
         </span>
       </div>
+      <div id="hotword-app-list" class="checkbox" hidden>
+        <label>
+          <input pref="hotword.app_list_enabled" type="checkbox">
+          <span i18n-content="enableHotwordAppList"></span>
+        </label>
+      </div>
 </if>
-      <div id ="hotword-search" hidden>
+      <div id="hotword-search" hidden>
         <div class="checkbox">
           <span class="controlled-setting-with-label">
             <input id="hotword-search-enable" pref="hotword.search_enabled"
                 metric="Options_HotwordCheckbox" type="checkbox" dialog-pref>
             <span>
               <label for="hotword-search-enable"
                   i18n-values=".innerHTML:hotwordSearchEnable">
               </label>
               <span class="controlled-setting-indicator"
                   pref="hotword.search_enabled" dialog-pref>
@@ skipping 517 matching lines @@
     </div>
   </section>
   </div>  <!-- advanced-settings-container -->
   </div>  <!-- advanced-settings -->
   <footer>
     <button id="advanced-settings-expander" class="link-button"
         i18n-content="showAdvancedSettings">
     </button>
   </footer>
   </div>