chromeos: Fix shelf appearing at login screen under mash

ash/mus/test/ash_test_impl_mus.cc

Index: ash/mus/test/ash_test_impl_mus.cc
diff --git a/ash/mus/test/ash_test_impl_mus.cc b/ash/mus/test/ash_test_impl_mus.cc
index 0f85cb703f290dcc04c4f1e408827b48405d78f9..043a4ed52010e8af3b3a007cff2002326adaddfc 100644
--- a/ash/mus/test/ash_test_impl_mus.cc
+++ b/ash/mus/test/ash_test_impl_mus.cc
@@ -4,8 +4,12 @@
 
 #include "ash/mus/test/ash_test_impl_mus.h"
 
+#include "ash/common/session/session_controller.h"
 #include "ash/common/test/ash_test.h"
+#include "ash/common/wm_shell.h"
 #include "ash/mus/bridge/wm_window_mus.h"
+#include "ash/public/cpp/session_types.h"
+#include "ash/public/interfaces/session_controller.mojom.h"
 #include "base/memory/ptr_util.h"
 #include "services/ui/public/cpp/property_type_converters.h"
 #include "services/ui/public/interfaces/window_manager.mojom.h"
@@ -40,6 +44,9 @@ AshTestImplMus::~AshTestImplMus() {}
 
 void AshTestImplMus::SetUp() {
   wm_test_base_->SetUp();
+
+  // Most tests assume the user is logged in (and hence the shelf is created).
+  SimulateUserLogin();
 }
 
 void AshTestImplMus::TearDown() {
@@ -100,6 +107,29 @@ void AshTestImplMus::AddTransientChild(WmWindow* parent, WmWindow* window) {
                           WmWindowAura::GetAuraWindow(window));
 }
 
+void AshTestImplMus::SimulateUserLogin() {
+  SessionController* session_controller = WmShell::Get()->session_controller();
+
+  // Simulate the first user logging in.
+  mojom::UserSessionPtr session = mojom::UserSession::New();
+  session->session_id = 1;
+  session->type = user_manager::USER_TYPE_REGULAR;
+  const std::string email("ash.user@example.com");
+  session->serialized_account_id = AccountId::FromUserEmail(email).Serialize();
+  session->display_name = "Ash User";
+  session->display_email = email;
+  session_controller->UpdateUserSession(std::move(session));
+
+  // Simulate the user session becoming active.
+  mojom::SessionInfoPtr info = mojom::SessionInfo::New();
+  info->max_users = 10;
+  info->can_lock_screen = true;
+  info->should_lock_screen_automatically = false;
+  info->add_user_session_policy = AddUserSessionPolicy::ALLOWED;
+  info->state = session_manager::SessionState::ACTIVE;
+  session_controller->SetSessionInfo(std::move(info));
+}
+
 }  // namespace mus
 
 // static