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

the window, at which point window_ is NULL. This can happen because
SHAppBarMessage runs a nested message loop pumping events. I suspect
the right fix is to not invoke SHAppBarMessage, but that'll have to be
done separately.

BUG=94614
TEST=none
R=ben@chromium.org

Review URL: http://codereview.chromium.org/7792014

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@98839 0039d316-1c4b-4281-b951-d872f2087c98

chrome/browser/ui/browser.cc

@@ -3927,7 +3927,11 @@ void Browser::Observe(int type,
 
     case chrome::NOTIFICATION_EXTENSION_UNINSTALLED:
     case chrome::NOTIFICATION_EXTENSION_LOADED:
-      if (window()->GetLocationBar())
+      // During window creation on Windows we may end up calling into
+      // SHAppBarMessage, which internally spawns a nested message loop. This
+      // makes it possible for us to end up here before window creation has
+      // completed,at which point window_ is NULL. See 94752 for details.
+      if (window() && window()->GetLocationBar())
         window()->GetLocationBar()->UpdatePageActions();
       break;