cros: Break BaseScreenHandler into two classes.

chrome/browser/ui/webui/chromeos/login/arc_kiosk_splash_screen_handler.cc

Index: chrome/browser/ui/webui/chromeos/login/arc_kiosk_splash_screen_handler.cc
diff --git a/chrome/browser/ui/webui/chromeos/login/arc_kiosk_splash_screen_handler.cc b/chrome/browser/ui/webui/chromeos/login/arc_kiosk_splash_screen_handler.cc
index 6533113070fdbe573bff67680f8b0123bc983d00..6b1ae2fd690e1809017a6f3a4e06cf430112fffb 100644
--- a/chrome/browser/ui/webui/chromeos/login/arc_kiosk_splash_screen_handler.cc
+++ b/chrome/browser/ui/webui/chromeos/login/arc_kiosk_splash_screen_handler.cc
@@ -24,7 +24,8 @@ constexpr char kJsScreenPath[] = "login.ArcKioskSplashScreen";
 
 namespace chromeos {
 
-ArcKioskSplashScreenHandler::ArcKioskSplashScreenHandler() {
+ArcKioskSplashScreenHandler::ArcKioskSplashScreenHandler()
+    : BaseScreenHandler(kScreenId) {
   set_call_js_prefix(kJsScreenPath);
 }
 
@@ -61,7 +62,7 @@ void ArcKioskSplashScreenHandler::Show() {
       base::MakeUnique<base::DictionaryValue>();
   PopulateAppInfo(app_info.get());
   data.Set("appInfo", std::move(app_info));
-  ShowScreenWithData(OobeScreen::SCREEN_ARC_KIOSK_SPLASH, &data);
+  ShowScreenWithData(kScreenId, &data);
 }
 
 void ArcKioskSplashScreenHandler::RegisterMessages() {