chromeos: Convert system tray session length limit to mojo

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 "ash/public/interfaces/user_info.mojom";
 import "components/signin/public/interfaces/account_id.mojom";
+import "mojo/common/time.mojom";
 
 // Matches session_manager::SessionState.
 enum SessionState {
   // Default value, when session state hasn't been initialized yet.
   UNKNOWN,
 
   // Running out of box UI.
   OOBE,
 
   // Running login UI (primary user) but user sign in hasn't completed yet.
@@ skipping 115 matching lines @@
   // event for locking. SessionController forwards it to PowerEventObserver.
   NotifyChromeLockAnimationsComplete();
 
   // Runs the pre-unlock animation. Invoked by the screen locker before
   // dismissing. When the mojo call returns, screen locker takes that as a
   // signal of finished unlock animation and dismisses itself.
   RunUnlockAnimation() => ();
 
   // Notifies that chrome is terminating.
   NotifyChromeTerminating();
+
+  // Adds a countdown timer to the system tray menu and creates or updates a
+  // notification saying the session length is limited (e.g. a public session in
+  // a library). Setting |length_limit| to zero removes the notification.
+  // NOTE: Chrome enforces the limit, not ash. Ash could enforce it if local
+  // state prefs and user activity monitoring were available under mustash.
+  // http://crbug.com/729808
+  SetSessionLengthLimit(mojo.common.mojom.TimeDelta length_limit,
+                        mojo.common.mojom.TimeTicks start_time);
 };
 
 // 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(signin.mojom.AccountId account_id);
 
   // Switch the active user to the next or previous user.
   CycleActiveUser(CycleUserDirection direction);
 };