Show different error message if ARC is disabled.

chrome/browser/chromeos/arc/arc_optin_uma.h

 // Copyright 2016 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_ARC_ARC_OPTIN_UMA_H_
 #define CHROME_BROWSER_CHROMEOS_ARC_ARC_OPTIN_UMA_H_
 
 #include <ostream>
 
 namespace base {
@@ skipping 94 matching lines @@
   OVERALL_SIGN_IN_TIMEOUT = 17,
 
   // In Chrome, server communication error occurs.
   // For backward compatibility, the UMA is handled differently. Please see
   // ArcSessionManager::OnProvisioningFinished for details.
   CHROME_SERVER_COMMUNICATION_ERROR = 18,
 
   // Network connection is unavailable in ARC.
   NO_NETWORK_CONNECTION = 19,
 
+  // ARC is not enabled.
+  ARC_DISABLED = 20,
+
   // The size of this enum; keep last.
   SIZE,
 };
 
 void UpdateOptInActionUMA(OptInActionType type);
 void UpdateOptInCancelUMA(OptInCancelReason reason);
 void UpdateEnabledStateUMA(bool enabled);
 void UpdateProvisioningResultUMA(ProvisioningResult result, bool managed);
 void UpdateProvisioningTiming(const base::TimeDelta& elapsed_time,
                               bool success,
                               bool managed);
 void UpdateSilentAuthCodeUMA(OptInSilentAuthCode state);
 void UpdateAuthTiming(const char* histogram_name, base::TimeDelta elapsed_time);
 void UpdateAuthCheckinAttempts(int32_t num_attempts);
 
 // Outputs the stringified |result| to |os|. This is only for logging purposes.
 std::ostream& operator<<(std::ostream& os, const ProvisioningResult& result);
 
 }  // namespace arc
 
 #endif  // CHROME_BROWSER_CHROMEOS_ARC_ARC_OPTIN_UMA_H_