Add Easy Unlock options to chrome://settings behind a flag.

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="chromeos">
   <include src="secondary_user_banner.html">
   <section>
     <div id="network-section-header" class="section-header">
@@ skipping 440 matching lines @@
               i18n-content="managePasswords">
           </button>
         </span>
       </span>
     </div>
 <if expr="is_macosx">
     <div id="mac-passwords-warning" i18n-content="macPasswordsWarning" hidden>
     </div>
 </if>
   </section>
+  <section id="easy-unlock-section" guest-visibility="hidden" hidden>
+    <h3 i18n-content="easyUnlockSectionTitle"></h3>
+    <!-- Options shown when the user has not set up Easy Unlock -->
+    <div id='easy-unlock-setup' hidden>
+      <button id="easy-unlock-setup-button"
+          i18n-content="easyUnlockSetupButton"></button>
+      <div>
+        <a target="_blank" i18n-content="learnMore"
+            i18n-values="href:easyUnlockLearnMoreURL"></a>
+      </div>
+    </div>
+    <!-- Options shown when the user has set up Easy Unlock -->
+    <div id='easy-unlock-enable' hidden>
+      <div class="checkbox">
+        <span class="controlled-setting-with-label">
+          <input id="easy-unlock-check" type="checkbox"
+              pref="easy_unlock.enabled"
+              metric="EasyUnlock_Enabled">
+          <span>
+            <label for="easy-unlock-checkbox">
+              <span i18n-content="easyUnlockCheckboxLabel"></span>
+              <a target="_blank" i18n-content="learnMore"
+                  i18n-values="href:easyUnlockLearnMoreURL"></a>
+            </label>
+            <span class="controlled-setting-indicator"
+                pref="easy_unlock.enabled">
+            </span>
+          </span>
+        </span>
+      </div>
+      <div>
+        <a target="_blank" i18n-content="easyUnlockManagement"
+            i18n-values="href:easyUnlockManagementURL"></a>
+      </div>
+    </div>
+  </section>
   <section id="web-content-section">
     <h3 i18n-content="advancedSectionTitleContent"></h3>
     <div>
       <div class="settings-row">
         <label class="web-content-select-label">
           <span i18n-content="defaultFontSizeLabel"></span>
           <select id="defaultFontSize">
             <option value="9" i18n-content="fontSizeLabelVerySmall">
             </option>
             <option value="12" i18n-content="fontSizeLabelSmall"></option>
@@ skipping 433 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>