aura: Require explicit ownership of the Env instance.

ash/test/ash_interactive_ui_test_base.cc

Index: ash/test/ash_interactive_ui_test_base.cc
diff --git a/ash/test/ash_interactive_ui_test_base.cc b/ash/test/ash_interactive_ui_test_base.cc
index b274c17c3bb2ee0245721a1f9079f988abe14150..ece27499d407581ceb3b881f89e171e608a0c0a2 100644
--- a/ash/test/ash_interactive_ui_test_base.cc
+++ b/ash/test/ash_interactive_ui_test_base.cc
@@ -29,14 +29,14 @@ void AshInteractiveUITestBase::SetUp() {
       resources_pack_path.Append(FILE_PATH_LITERAL("resources.pak"));
   ResourceBundle::GetSharedInstance().AddDataPackFromPath(
       resources_pack_path, ui::SCALE_FACTOR_NONE);
-  aura::Env::CreateInstance(true);
+  env_ = aura::Env::CreateInstance();
 
   test::AshTestBase::SetUp();
 }
 
 void AshInteractiveUITestBase::TearDown() {
   test::AshTestBase::TearDown();
-  aura::Env::DeleteInstance();
+  env_.reset();
 }
 
 }  // namespace test