chromeos: Fix shelf appearing at login screen under mash

ash/aura/wm_shell_aura.cc

Index: ash/aura/wm_shell_aura.cc
diff --git a/ash/aura/wm_shell_aura.cc b/ash/aura/wm_shell_aura.cc
index 2d59990720296339935609efaafa94c635b8b13c..e56e930174666c390bcb6f97cd90c98954f36833 100644
--- a/ash/aura/wm_shell_aura.cc
+++ b/ash/aura/wm_shell_aura.cc
@@ -246,6 +246,11 @@ void WmShellAura::OnOverviewModeEnded() {
     observer.OnOverviewModeEnded();
 }
 
+void WmShellAura::OnUserSessionStateActive() {
+  CreateShelf();

[msw, 2016/12/16 16:26:20]

It's a bit odd that we'll potentially call CreateShelf multiple times.

[James Cook, 2016/12/20 04:02:42]

OK, fixed that.

(I could also just rename this function to CreateShelfIfNeeded().)

+  Shell::GetInstance()->CreateKeyboard();

[msw, 2016/12/16 16:26:20]

Is this necessary here? Shouldn't it be triggered when the keyboard is needed?

[James Cook, 2016/12/20 04:02:42]

The virtual keyboard can be shown at the login screen before the shelf is shown,
but seems to destroy itself during login and needs to be recreated. It adds a
bunch of shelf-observers, so needs to be done after shelf creation. It also gets
torn down and recreated after multiprofile switch. It might be due to accessing
the active user's profile in the webui code.

Regardless, this is what the old code did and I'm afraid of breaking it.

+}
+
 SessionStateDelegate* WmShellAura::GetSessionStateDelegate() {
   return Shell::GetInstance()->session_state_delegate();
 }