Fixes crash in Browser::Observe. We can end up here during creation of

chrome/browser/ui/browser.cc

 // Copyright (c) 2011 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/browser.h"
 
 #if defined(OS_WIN)
 #include <windows.h>
 #include <shellapi.h>
 #endif  // OS_WIN
@@ skipping 3909 matching lines @@
     }
 
     case chrome::NOTIFICATION_EXTENSION_PROCESS_TERMINATED: {
       if (window()->GetLocationBar())
         window()->GetLocationBar()->InvalidatePageActions();
       break;
     }
 
     case chrome::NOTIFICATION_EXTENSION_UNINSTALLED:
     case chrome::NOTIFICATION_EXTENSION_LOADED:
-      if (window()->GetLocationBar())
+      // We can end up here when creating the window, at which point window_ is
+      // NULL.

[Ben Goodger (Google), 2011/08/30 17:19:49]

Add the rest of your CL comment here about SHAppBarMessage.

+      if (window() && window()->GetLocationBar())
         window()->GetLocationBar()->UpdatePageActions();
       break;
 
     case chrome::NOTIFICATION_BROWSER_THEME_CHANGED:
       window()->UserChangedTheme();
       break;
 
     case chrome::NOTIFICATION_EXTENSION_READY_FOR_INSTALL: {
       // Handle EXTENSION_READY_FOR_INSTALL for last active tabbed browser.
       if (BrowserList::FindTabbedBrowser(profile(), true) != this)
@@ skipping 1175 matching lines @@
 }
 
 void Browser::ShowSyncSetup() {
   ProfileSyncService* service =
       profile()->GetOriginalProfile()->GetProfileSyncService();
   if (service->HasSyncSetupCompleted())
     ShowOptionsTab(chrome::kSyncSetupSubPage);
   else
     service->ShowLoginDialog();
 }