aura: Require explicit ownership of the Env instance.

ui/aura/bench/bench_main.cc

Index: ui/aura/bench/bench_main.cc
diff --git a/ui/aura/bench/bench_main.cc b/ui/aura/bench/bench_main.cc
index f3a058a533aa8269f1a0eb677b4507696ce23284..158bde5e08f9b5932eda850408e1bfb73880d31f 100644
--- a/ui/aura/bench/bench_main.cc
+++ b/ui/aura/bench/bench_main.cc
@@ -309,8 +309,8 @@ int main(int argc, char** argv) {
   base::i18n::InitializeICU();
 
   base::MessageLoopForUI message_loop;
-  aura::Env::CreateInstance(true);
-  aura::Env::GetInstance()->set_context_factory(context_factory.get());
+  scoped_ptr<aura::Env> env = aura::Env::CreateInstance();
+  env->set_context_factory(context_factory.get());
   scoped_ptr<aura::TestScreen> test_screen(
       aura::TestScreen::CreateFullscreen());
   gfx::Screen::SetScreenInstance(gfx::SCREEN_TYPE_NATIVE, test_screen.get());