[Aura] Fix aura_shell_unittest ASAN errors.

Synchronously close launcher widget so that it will not access LauncherModel after Launcher is destructed.

BUG=104672
TEST=Verify aura_shell_unittest should pass ASAN.


Review URL: http://codereview.chromium.org/8589035

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@110628 0039d316-1c4b-4281-b951-d872f2087c98

ui/aura_shell/launcher/launcher.cc

@@ -42,6 +42,7 @@ Launcher::Launcher(aura::Window* window_container)
 }
 
 Launcher::~Launcher() {
+  widget_->CloseNow();
   window_container_->RemoveObserver(this);
   for (WindowMap::iterator i = known_windows_.begin();
        i != known_windows_.end(); ++i) {