aura: Require explicit ownership of the Env instance.

content/browser/browser_main_loop.cc

Index: content/browser/browser_main_loop.cc
diff --git a/content/browser/browser_main_loop.cc b/content/browser/browser_main_loop.cc
index e5ee0cfc3ae607054efc2437abbda88c43ac6914..d32c41d558d4a11e4375d79addbd1b8331dd0ba3 100644
--- a/content/browser/browser_main_loop.cc
+++ b/content/browser/browser_main_loop.cc
@@ -922,7 +922,7 @@ void BrowserMainLoop::ShutdownThreadsAndCleanUp() {
   }
 
 #if defined(USE_AURA)
-  aura::Env::DeleteInstance();
+  env_.reset();
 #endif
 
   trace_memory_controller_.reset();
@@ -1141,9 +1141,7 @@ int BrowserMainLoop::BrowserThreadsStarted() {
   BrowserGpuChannelHostFactory::Initialize(established_gpu_channel);
   ImageTransportFactory::Initialize();
 #if defined(USE_AURA)
-  if (aura::Env::GetInstance()) {
-    aura::Env::GetInstance()->set_context_factory(GetContextFactory());
-  }
+  env_->set_context_factory(GetContextFactory());
 #endif  // defined(USE_AURA)
 #endif  // defined(OS_ANDROID)
 
@@ -1288,7 +1286,7 @@ bool BrowserMainLoop::InitializeToolkit() {
 
   // Env creates the compositor. Aura widgets need the compositor to be created
   // before they can be initialized by the browser.
-  aura::Env::CreateInstance(true);
+  env_ = aura::Env::CreateInstance();
 #endif  // defined(USE_AURA)
 
   if (parts_)