Enable clang warning for ignored attributes.

components/domain_reliability/clear_mode.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 COMPONENTS_DOMAIN_RELIABILITY_CLEAR_MODE_H_
 #define COMPONENTS_DOMAIN_RELIABILITY_CLEAR_MODE_H_
 
 #include "components/domain_reliability/domain_reliability_export.h"
 
 namespace domain_reliability {
 
 // Argument to DomainReliabilityMonitor::ClearBrowsingData.
-enum DOMAIN_RELIABILITY_EXPORT DomainReliabilityClearMode {
+enum DomainReliabilityClearMode {
   // Clear accumulated beacons (which betray browsing history) but leave
   // registered contexts intact.
   CLEAR_BEACONS,
 
   // Clear registered contexts (which can act like cookies).
   CLEAR_CONTEXTS,
 
   MAX_CLEAR_MODE
 };
 
 }  // namespace domain_reliability
 
 #endif  // COMPONENTS_DOMAIN_RELIABILITY_CLEAR_MODE_H_