Add a mojo interface for AccountId

ash/public/interfaces/session_controller.mojom

 // 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.
 
 module ash.mojom;
 
+import "components/signin/public/interfaces/account_id.mojom";
 import "skia/public/interfaces/bitmap.mojom";
 
 // Matches session_manager::SessionState.
 enum SessionState {
   // Default value, when session state hasn't been initialized yet.
   UNKNOWN,
 
   // Running out of box UI.
   OOBE,
 
@@ skipping 49 matching lines @@
 
 // Info about a user session in ash.
 struct UserSession {
   // A user session id for the user session. It is generated by session manager
   // (chrome) when a user session starts and never changes during the lifetime
   // of the session manager. The number starts at 1 for the first user session
   // and incremented by one for each subsequent user session.
   uint32 session_id;
 
   UserType type;
-  string serialized_account_id;  // TODO(xiyuan): Use typemapping for AccountId.
+  signin.mojom.AccountId account_id;
   string display_name;
   string display_email;
   skia.mojom.Bitmap avatar;
 };
 
 // Matches ash::AddUserSessionPolicy.
 enum AddUserSessionPolicy {
   // Adding a user session is allowed.
   ALLOWED,
 
@@ skipping 45 matching lines @@
   SetUserSessionOrder(array<uint32> user_session_ids);
 };
 
 // Interface for ash to request session service from its client (e.g. Chrome).
 interface SessionControllerClient {
   // Requests to lock screen.
   RequestLockScreen();
 
   // Switch to the active user with |account_id| (if the user has already signed
   // in).
-  SwitchActiveUser(string account_id);
+  SwitchActiveUser(signin.mojom.AccountId account_id);
 
   // Switch the active user to the next or previous user.
   CycleActiveUser(bool next_user);
 };