aura: Require explicit ownership of the Env instance.

ui/aura/test/aura_test_helper.cc

Index: ui/aura/test/aura_test_helper.cc
diff --git a/ui/aura/test/aura_test_helper.cc b/ui/aura/test/aura_test_helper.cc
index 554f229a3c6ebc95429c7ee1296ecf31d73507d6..2d679e59f184c7f2248e374f1e65832776bb6b06 100644
--- a/ui/aura/test/aura_test_helper.cc
+++ b/ui/aura/test/aura_test_helper.cc
@@ -34,8 +34,7 @@ namespace test {
 
 AuraTestHelper::AuraTestHelper(base::MessageLoopForUI* message_loop)
     : setup_called_(false),
-      teardown_called_(false),
-      env_created_(false) {
+      teardown_called_(false) {
   DCHECK(message_loop);
   message_loop_ = message_loop;
   // Disable animations during tests.
@@ -57,10 +56,8 @@ AuraTestHelper::~AuraTestHelper() {
 void AuraTestHelper::SetUp(ui::ContextFactory* context_factory) {
   setup_called_ = true;
 
-  if (!Env::GetInstanceDontCreate()) {
-    env_created_ = true;
-    Env::CreateInstance(true);
-  }
+  if (!Env::GetInstanceDontCreate())
+    env_ = aura::Env::CreateInstance();
   Env::GetInstance()->set_context_factory(context_factory);
   // Unit tests generally don't want to query the system, rather use the state
   // from RootWindow.
@@ -103,8 +100,7 @@ void AuraTestHelper::TearDown() {
 
   ui::ShutdownInputMethodForTesting();
 
-  if (env_created_)
-    Env::DeleteInstance();
+  env_.reset();
 }
 
 void AuraTestHelper::RunAllPendingInMessageLoop() {