Add UMA stats for user settings

chrome/browser/resources/options/chromeos/accounts_options.html

 <div id="accountsPage" class="page" hidden>
   <div class="close-button"></div>
   <h1 i18n-content="accountsPage"></h1>
   <div class="content-area">
     <div class="option">
       <div id="ownerOnlyWarning" hidden>
         <span i18n-content="owner_only"></span>
         <span i18n-content="ownerUserId"></span>
       </div>
       <table class="option-control-table">
       <tr>
         <td class="option-name">
           <div class="checkbox">
             <label>
-              <input id="allowBwsiCheck" pref="cros.accounts.allowBWSI"
-                  type="checkbox">
+              <input id="allowBwsiCheck" type="checkbox"
+                     metric="Options_GuestBrowsing"
+                     pref="cros.accounts.allowBWSI">
               <span i18n-content="allow_BWSI"></span>
             </label>
           </div>
         </td>
       </tr>
       <tr>
         <td class="option-name">
           <div class="checkbox">
              <label>
-              <input id="allowSupervisedCheck"
-                  pref="cros.accounts.supervisedUsersEnabled" type="checkbox">
+              <input id="allowSupervisedCheck" type="checkbox"
+                     metric="Options_SupervisedUsers"
+                     pref="cros.accounts.supervisedUsersEnabled">
               <span i18n-content="allow_supervised_users"></span>
             </label>
           </div>
         </td>
       </tr>
       <tr>
         <td class="option-name">
           <div class="checkbox">
             <label>
-              <input id="showUserNamesCheck"
-                  pref="cros.accounts.showUserNamesOnSignIn" type="checkbox">
+              <input id="showUserNamesCheck" type="checkbox"
+                     metric="Options_ShowUserNamesOnSignin"
+                     pref="cros.accounts.showUserNamesOnSignIn">
               <span i18n-content="show_user_on_signin"></span>
             </label>
           </div>
         </td>
       </tr>
       <tr>
         <td class="option-name">
           <div class="checkbox">
             <label>
-              <input id="useWhitelistCheck" pref="cros.accounts.allowGuest"
-                  type="checkbox" inverted_pref>
+              <input id="useWhitelistCheck" type="checkbox"
+                     metric="Options_AllowAllUsers"
+                     pref="cros.accounts.allowGuest"
+                     inverted_pref>
               <span i18n-content="use_whitelist"></span>
             </label>
           </div>
         </td>
       </tr>
       <tr><td>&nbsp;</td></tr>
       <tr><td>
         <table class="user-list-table">
           <tr><td>
             <list id="userList"></list>
@@ skipping 11 matching lines @@
     </div>
   </div>
   <div class="action-area">
     <div class="button-strip">
       <button id="accounts-options-overlay-confirm" class="default-button"
           i18n-content="done">
       </button>
     </div>
   </div>
 </div>