cros: Break BaseScreenHandler into two classes.

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

 // 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_HOST_PAIRING_SCREEN_VIEW_H_
 #define CHROME_BROWSER_CHROMEOS_LOGIN_SCREENS_HOST_PAIRING_SCREEN_VIEW_H_
 
 #include "base/macros.h"
+#include "chrome/browser/chromeos/login/oobe_screen.h"
 
 namespace base {
 class DictionaryValue;
 }
 
 namespace chromeos {
 
 namespace host_pairing {
 
 // Keep these constants synced with corresponding constants defined in
@@ skipping 21 matching lines @@
 }  // namespace host_pairing
 
 class HostPairingScreenView {
  public:
   class Delegate {
    public:
     virtual ~Delegate() {}
     virtual void OnViewDestroyed(HostPairingScreenView* view) = 0;
   };
 
+  constexpr static OobeScreen kScreenId = OobeScreen::SCREEN_OOBE_HOST_PAIRING;
+
   HostPairingScreenView();
   virtual ~HostPairingScreenView();
 
   virtual void Show() = 0;
   virtual void Hide() = 0;
   virtual void SetDelegate(Delegate* delegate) = 0;
   virtual void OnContextChanged(const base::DictionaryValue& diff) = 0;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(HostPairingScreenView);
 };
 
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_CHROMEOS_LOGIN_SCREENS_HOST_PAIRING_SCREEN_VIEW_H_