Add mac-only "Set Up Automatic Updates..." button to the new about page.

chrome/browser/ui/webui/help/version_updater_mac.mm

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/ui/webui/help/version_updater_mac.h"
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/logging.h"
 #include "base/mac/foundation_util.h"
@@ skipping 219 matching lines @@
       message += l10n_util::GetStringUTF16(IDS_UPGRADE_ERROR_DETAILS);
       message += base::UTF8ToUTF16("<br/><pre>");
       message += base::UTF8ToUTF16(net::EscapeForHTML(error_messages));
       message += base::UTF8ToUTF16("</pre>");
     }
   }
 
   if (!status_callback_.is_null())
     status_callback_.Run(status, 0, message);
 
+  PromotionState promotion_state;
   if (!promote_callback_.is_null()) {
-    PromotionState promotion_state = PROMOTE_HIDDEN;
-    if (show_promote_button_)
-      promotion_state = enable_promote_button ? PROMOTE_ENABLED
-                                              : PROMOTE_DISABLED;
+    KeystoneGlue* keystone_glue = [KeystoneGlue defaultKeystoneGlue];
+    if (keystone_glue && [keystone_glue isAutoupdateEnabledForAllUsers]) {
+      promotion_state = PROMOTED;
+    } else {
+      promotion_state = PROMOTE_HIDDEN;
+
+      if (show_promote_button_) {
+        promotion_state = enable_promote_button ? PROMOTE_ENABLED
+                                                : PROMOTE_DISABLED;
+      }
+    }
+
     promote_callback_.Run(promotion_state);
   }
 }
 
 void VersionUpdaterMac::UpdateShowPromoteButton() {
   if (ObsoleteSystem::IsObsoleteNowOrSoon()) {
     // Promotion is moot upon reaching the end of the line.
     show_promote_button_ = false;
     return;
   }
 
   KeystoneGlue* keystone_glue = [KeystoneGlue defaultKeystoneGlue];
   AutoupdateStatus recent_status = [keystone_glue recentStatus];
   if (recent_status == kAutoupdateRegistering ||
       recent_status == kAutoupdateRegisterFailed ||
       recent_status == kAutoupdatePromoted) {
     // Promotion isn't possible at this point.
     show_promote_button_ = false;
   } else if (recent_status == kAutoupdatePromoting ||
              recent_status == kAutoupdatePromoteFailed) {
     // Show promotion UI because the user either just clicked that button or
     // because the user should be able to click it again.
     show_promote_button_ = true;
   } else {
     // Show the promote button if promotion is a possibility.
     show_promote_button_ = [keystone_glue wantsPromotion];
   }
 }