Added login screen mode for adding users into session.

chrome/browser/chromeos/login/user_adding_screen.h

+// Copyright (c) 2013 The Chromium Authors. All rights reserved.

[Nikita (slow), 2013/05/28 11:34:22]

To make name more consistent this could be renamed to
add_user_to_session_screen.
Will that work?

[dzhioev (left Google), 2013/05/29 13:05:04]

Decided to leave current name.

+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CHROME_BROWSER_CHROMEOS_LOGIN_USER_ADDING_SCREEN_H_
+#define CHROME_BROWSER_CHROMEOS_LOGIN_USER_ADDING_SCREEN_H_
+
+#include "base/basictypes.h"
+
+namespace chromeos {
+
+// An interface that defines screen for adding users into multiprofile session.

[Nikita (slow), 2013/05/28 11:34:22]

nit: multi-profile

[dzhioev (left Google), 2013/05/29 13:05:04]

Done.

+// Current implementation is singleton.

[Nikita (slow), 2013/05/28 11:34:22]

nit: Please add TODO to came up with a better design for this and ideally get
rid of singleton.

[Nikita (slow), 2013/05/28 11:34:22]

nit: is a

[dzhioev (left Google), 2013/05/29 13:05:04]

Done.

[dzhioev (left Google), 2013/05/29 13:05:04]

Done.

+class UserAddingScreen {
+ public:
+  struct Observer {
+    virtual void OnUserAddingStarted() {}

[Nikita (slow), 2013/05/28 11:34:22]

Body should go to .cc

[dzhioev (left Google), 2013/05/29 13:05:04]

I think it is OK to leave empty definitions of Observer's methods in header. I
saw such thing in many other places: PowerManagerClient::Observer,
BluetoothAdapter::Observer, etc.

[Nikita (slow), 2013/05/29 13:29:38]

I think that violates
http://dev.chromium.org/developers/coding-style#TOC-Inline-functions

+    virtual void OnUserAddingFinished() {}
+    virtual ~Observer() {}
+  };
+
+  static UserAddingScreen* Get();
+
+  virtual void Start() = 0;
+  virtual void Cancel() = 0;
+  virtual bool IsRunning() = 0;
+
+  virtual void AddObserver(Observer* observer) = 0;
+  virtual void RemoveObserver(Observer* observer) = 0;
+
+ protected:
+  UserAddingScreen();
+  virtual ~UserAddingScreen();
+
+  DISALLOW_COPY_AND_ASSIGN(UserAddingScreen);
+};
+
+}  // namespace chromeos
+
+#endif  // CHROME_BROWSER_CHROMEOS_LOGIN_USER_ADDING_SCREEN_H_
+