session_manager: Tracks user sessions

components/session_manager/session_manager_types.h

Index: components/session_manager/session_manager_types.h
diff --git a/components/session_manager/session_manager_types.h b/components/session_manager/session_manager_types.h
index 5b30a837ccc35257f14c1961d027e8e2e3bfa594..93e29745d4228ad36325b28c5be625811537e76d 100644
--- a/components/session_manager/session_manager_types.h
+++ b/components/session_manager/session_manager_types.h
@@ -5,6 +5,8 @@
 #ifndef COMPONENTS_SESSION_MANAGER_SESSION_MANAGER_TYPES_H_
 #define COMPONENTS_SESSION_MANAGER_SESSION_MANAGER_TYPES_H_
 
+#include "components/signin/core/account_id/account_id.h"
+
 namespace session_manager {
 
 // TODO(xiyuan): Get rid/consolidate with chromeos::LoggedInState.
@@ -34,6 +36,15 @@ enum class SessionState {
   LOGIN_SECONDARY,
 };
 
+// A type for session id.
+using SessionId = int;
+
+// Info about a user session.
+struct Session {
+  SessionId id;
+  AccountId user_account_id;
+};
+
 }  // namespace session_manager
 
 #endif  // COMPONENTS_SESSION_MANAGER_SESSION_MANAGER_TYPES_H_