Tray elements behave appropriately on the multiple signin screen (more like lock screen)

ash/shell/shell_delegate_impl.cc

 // Copyright (c) 2012 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/shell/shell_delegate_impl.h"
 
 #include "ash/accessibility_delegate.h"
 #include "ash/default_accessibility_delegate.h"
 #include "ash/default_user_wallpaper_delegate.h"
 #include "ash/gpu_support_stub.h"
@@ skipping 140 matching lines @@
   virtual bool ShouldShowAvatar(aura::Window* window) const OVERRIDE {
     return !user_info_->GetImage().isNull();
   }
   virtual void SwitchActiveUser(const std::string& user_id) OVERRIDE {}
   virtual void CycleActiveUser(CycleUser cycle_user) OVERRIDE {}
   virtual void AddSessionStateObserver(
       ash::SessionStateObserver* observer) OVERRIDE {}
   virtual void RemoveSessionStateObserver(
       ash::SessionStateObserver* observer) OVERRIDE {}
 
+  virtual void HideMultipleSigninScreen() OVERRIDE {}
+
  private:
   bool screen_locked_;
 
   // A pseudo user info.
   scoped_ptr<UserInfo> user_info_;
 
   DISALLOW_COPY_AND_ASSIGN(SessionStateDelegateImpl);
 };
 
 }  // namespace
@@ skipping 107 matching lines @@
   // Real GPU support depends on src/content, so just use a stub.
   return new GPUSupportStub;
 }
 
 base::string16 ShellDelegateImpl::GetProductName() const {
   return base::string16();
 }
 
 }  // namespace shell
 }  // namespace ash