[Mac] Make initial visibility of the promote button on the about page deterministic

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 "chrome/browser/lifetime/application_lifetime.h"
 #import "chrome/browser/mac/keystone_glue.h"
@@ skipping 39 matching lines @@
   versionUpdater_->UpdateStatus([notification userInfo]);
 }
 
 @end  // @implementation KeystoneObserver
 
 
 VersionUpdater* VersionUpdater::Create() {
   return new VersionUpdaterMac;
 }
 
-VersionUpdaterMac::VersionUpdaterMac() {
-  keystone_observer_.reset([[KeystoneObserver alloc] initWithUpdater:this]);
+VersionUpdaterMac::VersionUpdaterMac()
+    : show_promote_button_(false),
+      keystone_observer_([[KeystoneObserver alloc] initWithUpdater:this]) {
 }
 
 VersionUpdaterMac::~VersionUpdaterMac() {
 }
 
 void VersionUpdaterMac::CheckForUpdate(
     const StatusCallback& status_callback,
     const PromoteCallback& promote_callback) {
   // Copy the callbacks, we will re-use this for the remaining lifetime
   // of this object.
@@ skipping 160 matching lines @@
   } 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];
   }
 }