chromeos: Fix shelf appearing at login screen under mash

ash/mus/bridge/wm_shell_mus.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ash/mus/bridge/wm_shell_mus.h"
 
 #include <utility>
 
 #include "ash/common/accelerators/accelerator_controller.h"
 #include "ash/common/key_event_watcher.h"
@@ skipping 374 matching lines @@
 void WmShellMus::OnOverviewModeStarting() {
   for (auto& observer : *shell_observers())
     observer.OnOverviewModeStarting();
 }
 
 void WmShellMus::OnOverviewModeEnded() {
   for (auto& observer : *shell_observers())
     observer.OnOverviewModeEnded();
 }
 
+void WmShellMus::OnUserSessionStateActive() {
+  CreateShelf();
+  // Mash has a different codepath for virtual keyboard initialization.

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

This comment is a bit odd, since nothing keyboard related is happening here.
Remove the comment or provide some context, like "WmShelAura initializes the
Keyboard at this stage, but Mash does so elsewhere."

[James Cook, 2016/12/20 04:02:43]

This codepath doesn't exist anymore.

+}
+
 SessionStateDelegate* WmShellMus::GetSessionStateDelegate() {
   return session_state_delegate_.get();
 }
 
 void WmShellMus::AddActivationObserver(WmActivationObserver* observer) {
   activation_observers_.AddObserver(observer);
 }
 
 void WmShellMus::RemoveActivationObserver(WmActivationObserver* observer) {
   activation_observers_.RemoveObserver(observer);
@@ skipping 53 matching lines @@
   WmWindow* gained_active_wm = WmWindowMus::Get(gained_active);
   if (gained_active_wm)
     set_root_window_for_new_windows(gained_active_wm->GetRootWindow());
   WmWindow* lost_active_wm = WmWindowMus::Get(lost_active);
   for (auto& observer : activation_observers_)
     observer.OnWindowActivated(gained_active_wm, lost_active_wm);
 }
 
 }  // namespace mus
 }  // namespace ash