Explicit initialization of aura::Env for browser shell.

ui/aura/env.cc

Index: ui/aura/env.cc
diff --git a/ui/aura/env.cc b/ui/aura/env.cc
index 6b2b3e023a3dbd9a6dc1df81e02f409df2eb5615..016886bf74e6f67af1db566558660015ccf77af2 100644
--- a/ui/aura/env.cc
+++ b/ui/aura/env.cc
@@ -39,12 +39,18 @@ Env::~Env() {
   ui::Compositor::Terminate();
 }
 
-// static
-Env* Env::GetInstance() {
+//static
+void Env::CreateInstance() {
   if (!instance_) {

[dnicoara, 2013/09/10 19:15:00]

I would have liked to have this as a check and only allow calls to  this
function only when |instance_| hasn't been created unfortunately call ordering
in tests (see comment in ash_test_helper.cc) doesn't allow it. This would also
depend on moving the aura::Env::CreateInstance call in aura::RootWindow to
content::MinimalShell, though I think we don't want to do that since we want
creation as close as possible to first use.

     instance_ = new Env;
     instance_->Init();
   }
+}
+
+// static
+Env* Env::GetInstance() {
+  DCHECK(instance_) << "Env::CreateInstance must be called before getting "
+                       "the instance of Env.";
   return instance_;
 }