user_manager: Remove deps on session_manager

chrome/browser/ui/ash/session_state_delegate_chromeos.cc

Index: chrome/browser/ui/ash/session_state_delegate_chromeos.cc
diff --git a/chrome/browser/ui/ash/session_state_delegate_chromeos.cc b/chrome/browser/ui/ash/session_state_delegate_chromeos.cc
index 843f2da832529e72be320e1e8ee39f78217380d0..a0c495ef8212941b0526b7061f849fa5a4cc281a 100644
--- a/chrome/browser/ui/ash/session_state_delegate_chromeos.cc
+++ b/chrome/browser/ui/ash/session_state_delegate_chromeos.cc
@@ -26,6 +26,7 @@
 #include "chromeos/dbus/session_manager_client.h"
 #include "chromeos/login/login_state.h"
 #include "components/prefs/pref_service.h"
+#include "components/session_manager/core/session_manager.h"
 #include "components/signin/core/account_id/account_id.h"
 #include "components/user_manager/user.h"
 #include "components/user_manager/user_info.h"
@@ -89,7 +90,8 @@ bool SessionStateDelegateChromeos::CanAddUserToMultiProfile(
 }
 
 bool SessionStateDelegateChromeos::IsActiveUserSessionStarted() const {
-  return user_manager::UserManager::Get()->IsSessionStarted();
+  return session_manager::SessionManager::Get() &&
+         session_manager::SessionManager::Get()->IsSessionStarted();
 }
 
 bool SessionStateDelegateChromeos::CanLockScreen() const {