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"
+                     metric="Options_EnableGuestBrowsing"
+                     pref="cros.accounts.allowBWSI"
+                     type="checkbox">

[michaelpg, 2014/06/13 23:15:43]

nit: You could fit this and the ones below in 2-3 lines instead of 4. Looking at
browser_options.html there doesn't seem to be any consistent attribute ordering
being enforced.

[stevenjb, 2014/06/16 21:58:10]

I moved type next to id for brevity but I prefer the order within the file being
consistent.

               <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">
+                     metric="Options_EnableSupervisedUsers"
+                     pref="cros.accounts.supervisedUsersEnabled"
+                     type="checkbox">
               <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">
+                     metric="Options_ShowUserNamesOnSignin"
+                     pref="cros.accounts.showUserNamesOnSignIn"
+                     type="checkbox">
               <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"
+                     metric="Options_RestrictUsers"
+                     pref="cros.accounts.allowGuest"
+                     type="checkbox" inverted_pref>

[michaelpg, 2014/06/13 23:15:43]

This is an inverted_pref, which changes the value reported but apparently
doesn't change the way the metric is reported (see
pref_ui.js:updatePrefFromState_ and CoreOptionsHandler::ProcessUserMetric).

"RestrictUsers" is the inverse of the pref name, "allowGuest", so checking this
box should trigger "Options_RestrictUsers_Enable" even though it sets allowGuest
to false. But in actuality, I think it will log "Options_RestrictUsers_Disable".

The easiest way to get around this would be to just rename this
"Options_AllowAllUsers" or something (because the name allowGuest isn't
accurate), so it also inverts the checkbox's meaning.

[stevenjb, 2014/06/16 21:58:10]

Done.

               <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>