Turn web intents build flag on. Move the command-line flag to default on.

chrome/browser/resources/options2/content_settings.html

 <div id="content-settings-page" class="page" hidden>
   <header><h1 i18n-content="contentSettingsPage"></h1></header>
   <div class="displaytable">
     <!-- Cookie filter tab contents -->
     <section>
       <h3 i18n-content="cookies_tab_label"></h3>
       <div>
         <div class="radio">
           <label>
             <input type="radio" name="cookies" value="allow">
@@ skipping 228 matching lines @@
           <label>
             <input type="radio" name="mouselock" value="block">
             <span i18n-content="mouselock_block"></span>
           </label>
         </div>
         <button class="exceptions-list-button" contentType="mouselock"
             i18n-content="manage_exceptions"></button>
       </div>
     </section>
     <!-- Intent registration filter tab contents -->
-    <if expr="pp_ifdef('enable_web_intents')">
+    <if expr="pp_ifdef('enable_web_intents_tag')">
       <section id="intents-section">
       <h3 i18n-content="intentsTabLabel" class="content-settings-header"></h3>
         <div>
           <div class="radio">
             <label>
               <input type="radio" name="intents" value="allow">
               <span i18n-content="intentsAllow"></span>
             </label>
           </div>
           <div class="radio">
@@ skipping 10 matching lines @@
           </div>
           <button class="exceptions-list-button" contentType="intents"
               i18n-content="manage_exceptions"></button>
           <button id="manage-intents-button" contentType="intents"
               i18n-content="manageIntents"></button>
         </div>
       </section>
     </if>
   </div>
 </div>