Protect status_area_ access

Change-Id: Ie6ee3ec84c126f46cdc34aea17bafa43cd49245c

BUG=chromium-os:23709
TEST=Chrome starts + VMTests pass


Review URL: http://codereview.chromium.org/8785011

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@112845 0039d316-1c4b-4281-b951-d872f2087c98

chrome/browser/chromeos/login/webui_login_view.cc

@@ -269,7 +269,8 @@ StatusAreaButton::TextStyle WebUILoginView::GetStatusAreaTextStyle() const {
 }
 
 void WebUILoginView::ButtonVisibilityChanged(views::View* button_view) {
-  status_area_->UpdateButtonVisibility();
+  if (status_area_)
+    status_area_->UpdateButtonVisibility();
 }
 
 void WebUILoginView::OnRenderHostCreated(RenderViewHost* host) {