1 files changed, 46 insertions, 0 deletions
diff --git a/ash/session/session_state_observer.h b/ash/session/session_state_observer.h
new file mode 100644
index 0000000..36fad83
--- /dev/null
+++ b/ash/session/session_state_observer.h
@@ -0,0 +1,46 @@
+// 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_SESSION_STATE_OBSERVER_H_
+#define ASH_SESSION_SESSION_STATE_OBSERVER_H_
+
+#include <string>
+
+#include "ash/ash_export.h"
+#include "ash/session/session_state_delegate.h"
+#include "base/basictypes.h"
+
+namespace ash {
+
+class ASH_EXPORT SessionStateObserver {
+ public:
+  // Called when active user has changed.
+  virtual void ActiveUserChanged(const std::string& user_id) {}
+
+  // Called when another user gets added to the existing session.
+  virtual void UserAddedToSession(const std::string& user_id) {}
+
+  // Called when session state is changed.
+  virtual void SessionStateChanged(SessionStateDelegate::SessionState state) {}
+
+ protected:
+  virtual ~SessionStateObserver() {}
+};
+
+// A class to attach / detach an object as a session state observer with a
+// scoped pointer.
+class ASH_EXPORT ScopedSessionStateObserver {
+ public:
+  explicit ScopedSessionStateObserver(ash::SessionStateObserver* observer);
+  virtual ~ScopedSessionStateObserver();
+
+ private:
+  ash::SessionStateObserver* observer_;
+
+  DISALLOW_COPY_AND_ASSIGN(ScopedSessionStateObserver);
+};
+
+}  // namespace ash
+
+#endif  // ASH_SESSION_SESSION_STATE_OBSERVER_H_