Fix crash in shutdown of cast_shell browser process

chromecast/browser/cast_browser_main_parts.cc

Index: chromecast/browser/cast_browser_main_parts.cc
diff --git a/chromecast/browser/cast_browser_main_parts.cc b/chromecast/browser/cast_browser_main_parts.cc
index cab3c615d3702537ca79f272f0182d0472eb2c05..91b13cef9f7d444841170c1d41f28f7a79b79e84 100644
--- a/chromecast/browser/cast_browser_main_parts.cc
+++ b/chromecast/browser/cast_browser_main_parts.cc
@@ -55,6 +55,7 @@
 #endif
 
 #if defined(USE_AURA)
+#include "ui/aura/env.h"
 #include "ui/aura/test/test_screen.h"
 #include "ui/gfx/screen.h"
 #endif
@@ -373,6 +374,11 @@ void CastBrowserMainParts::PostMainMessageLoopRun() {
   cast_browser_process_->cast_service()->Finalize();
   cast_browser_process_->metrics_service_client()->Finalize();
   cast_browser_process_.reset();
+
+#if defined(USE_AURA)
+  aura::Env::DeleteInstance();
+#endif
+
   DeregisterKillOnAlarm();
 #endif