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 2effbd75c8ca0bd35d80f9c7818a447a80a9d1a2..65e88aced2e3117ad82bb6682e2fccfdfa859280 100644
--- a/content/browser/browser_main_loop.cc
+++ b/content/browser/browser_main_loop.cc
@@ -982,7 +982,7 @@ void BrowserMainLoop::ShutdownThreadsAndCleanUp() {
   }
 
 #if defined(USE_AURA)
-  aura::Env::DeleteInstance();
+  env_.reset();
 #endif
 
   system_stats_monitor_.reset();
@@ -1366,7 +1366,7 @@ 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_)