cros: Move BaseScreenDelegate::ExitCodes into separate file, ScreenExitCode.

chrome/browser/chromeos/login/screens/eula_screen.cc

Index: chrome/browser/chromeos/login/screens/eula_screen.cc
diff --git a/chrome/browser/chromeos/login/screens/eula_screen.cc b/chrome/browser/chromeos/login/screens/eula_screen.cc
index e17cc1ea3e67c86384a08856bec681b2f8ae5c29..231dfb6ed9da895e4fb3f89af3edb7939b9c6f2f 100644
--- a/chrome/browser/chromeos/login/screens/eula_screen.cc
+++ b/chrome/browser/chromeos/login/screens/eula_screen.cc
@@ -98,9 +98,9 @@ void EulaScreen::Hide() {
 
 void EulaScreen::OnUserAction(const std::string& action_id) {
   if (action_id == kUserActionAcceptButtonClicked)
-    Finish(BaseScreenDelegate::EULA_ACCEPTED);
+    Finish(ScreenExitCode::EULA_ACCEPTED);
   else if (action_id == kUserActionBackButtonClicked)
-    Finish(BaseScreenDelegate::EULA_BACK);
+    Finish(ScreenExitCode::EULA_BACK);
   else
     BaseScreen::OnUserAction(action_id);
 }