Simplify adding callbacks.

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

Index: chrome/browser/ui/webui/chromeos/login/enterprise_oauth_enrollment_screen_handler.cc
diff --git a/chrome/browser/ui/webui/chromeos/login/enterprise_oauth_enrollment_screen_handler.cc b/chrome/browser/ui/webui/chromeos/login/enterprise_oauth_enrollment_screen_handler.cc
index ddf2e0b5d72b76fffee900f70ccff39d0d4b2e3c..0efbc6d95973fe7ad7796d9cedbe38fb1741e668 100644
--- a/chrome/browser/ui/webui/chromeos/login/enterprise_oauth_enrollment_screen_handler.cc
+++ b/chrome/browser/ui/webui/chromeos/login/enterprise_oauth_enrollment_screen_handler.cc
@@ -377,11 +377,7 @@ void EnterpriseOAuthEnrollmentScreenHandler::OnBrowsingDataRemoverDone() {
 // EnterpriseOAuthEnrollmentScreenHandler, private -----------------------------
 
 void EnterpriseOAuthEnrollmentScreenHandler::HandleClose(
-    const base::ListValue* value) {
-  std::string reason;
-  CHECK_EQ(1U, value->GetSize());
-  CHECK(value->GetString(0, &reason));
-
+    const std::string& reason) {
   if (!controller_) {
     NOTREACHED();
     return;
@@ -398,28 +394,19 @@ void EnterpriseOAuthEnrollmentScreenHandler::HandleClose(
 }
 
 void EnterpriseOAuthEnrollmentScreenHandler::HandleCompleteLogin(
-    const base::ListValue* value) {
+    const std::string& user) {
   if (!controller_) {
     NOTREACHED();
     return;
   }
-
-  std::string user;
-  if (!value->GetString(0, &user)) {
-    NOTREACHED() << "Invalid user parameter from UI.";
-    return;
-  }
-
   controller_->OnLoginDone(gaia::SanitizeEmail(user));
 }
 
-void EnterpriseOAuthEnrollmentScreenHandler::HandleRetry(
-    const base::ListValue* value) {
+void EnterpriseOAuthEnrollmentScreenHandler::HandleRetry() {
   if (!controller_) {
     NOTREACHED();
     return;
   }
-
   controller_->OnRetry();
 }