Add ash SessionStateDelegate

ash/session_state_delegate.h

+// Copyright (c) 2013 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.
+
+#ifndef ASH_SESSION_STATE_DELEGATE_H_
+#define ASH_SESSION_STATE_DELEGATE_H_
+
+#include "ash/ash_export.h"
+
+namespace ash {
+
+// Delegate for checking and modifying the session state.
+class ASH_EXPORT SessionStateDelegate {
+ public:
+  virtual ~SessionStateDelegate() {};
+
+  // Returns |true| if a session is in progress and there is an active user.
+  virtual bool HasActiveUser() const = 0;
+
+  // Returns |true| if the session has been fully started for the active user.
+  // When a user becomes active, the profile and browser UI are not immediately
+  // available. Only once this method starts returning |true| is the browser
+  // startup complete and both profile and UI are fully available.
+  virtual bool IsActiveUserSessionStarted() const = 0;
+
+  // Returns true if the screen can be locked.
+  virtual bool CanLockScreen() const = 0;
+
+  // Returns true if the screen is currently locked.
+  virtual bool IsScreenLocked() const = 0;
+
+  // Locks the screen.

[Daniel Erat, 2013/04/16 17:34:15]

nit: mention that is possibly asynchronous

[bartfab (slow), 2013/04/17 08:14:41]

Done.

+  virtual void LockScreen() = 0;
+
+  // Unlocks the screen.
+  virtual void UnlockScreen() = 0;
+};
+
+}  // namespace ash
+
+#endif  // ASH_SESSION_STATE_DELEGATE_H_