Example of usage of new features of context and screen.

chrome/browser/chromeos/login/screens/controller_pairing_screen.h

Index: chrome/browser/chromeos/login/screens/controller_pairing_screen.h
diff --git a/chrome/browser/chromeos/login/screens/controller_pairing_screen.h b/chrome/browser/chromeos/login/screens/controller_pairing_screen.h
new file mode 100644
index 0000000000000000000000000000000000000000..f9443f5a48a3e2e13334a95a6735546765ed2f30
--- /dev/null
+++ b/chrome/browser/chromeos/login/screens/controller_pairing_screen.h
@@ -0,0 +1,58 @@
+// Copyright 2014 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 CHROME_BROWSER_CHROMEOS_LOGIN_SCREENS_CONTROLLER_PAIRING_SCREEN_H_
+#define CHROME_BROWSER_CHROMEOS_LOGIN_SCREENS_CONTROLLER_PAIRING_SCREEN_H_
+
+#include "base/macros.h"
+
+#include "chrome/browser/chromeos/login/screens/controller_pairing_screen_actor.h"
+#include "chrome/browser/chromeos/login/screens/screen_context.h"
+#include "chrome/browser/chromeos/login/screens/wizard_screen.h"
+#include "chromeos/pairing/controller_pairing_flow.h"
+
+namespace chromeos {
+
+class ControllerPairingScreen : public WizardScreen,
+                                public ControllerPairingFlow::Observer,
+                                public ControllerPairingScreenActor::Delegate {
+ public:
+  ControllerPairingScreen(ScreenObserver* observer,
+                          ControllerPairingScreenActor* actor);
+  virtual ~ControllerPairingScreen();
+
+ private:
+  typedef ControllerPairingFlow::Stage Stage;
+
+  void CommitContextChanges();
+  bool ExpectStageIs(Stage stage) const;
+
+  // Overridden from WizardScreen:
+  virtual void PrepareToShow() OVERRIDE;
+  virtual void Show() OVERRIDE;
+  virtual void Hide() OVERRIDE;
+  virtual std::string GetName() const OVERRIDE;
+
+  // Overridden from ControllerPairingFlow::Observer:
+  virtual void PairingStageChanged(Stage new_stage) OVERRIDE;
+  virtual void DiscoveredDevicesListChanged() OVERRIDE;
+
+  // Overridden from ControllerPairingView::Delegate:
+  virtual void OnActorDestroyed(ControllerPairingScreenActor* actor) OVERRIDE;
+  virtual void OnScreenContextChanged(
+      const base::DictionaryValue& diff) OVERRIDE;
+  virtual void OnButtonClicked(const std::string& action) OVERRIDE;
+
+  ScreenContext context_;
+  ControllerPairingScreenActor* actor_;
+  scoped_ptr<ControllerPairingFlow> flow_;
+  Stage current_stage_;
+  bool device_preselected_;
+
+  DISALLOW_COPY_AND_ASSIGN(ControllerPairingScreen);
+};
+
+}  // namespace chromeos
+
+#endif  // CHROME_BROWSER_CHROMEOS_LOGIN_SCREENS_CONTROLLER_PAIRING_SCREEN_H_