Clean up sparse_histogram.h header

chrome/browser/chromeos/login/enrollment/enrollment_uma.cc

 // 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.
 
 #include "chrome/browser/chromeos/login/enrollment/enrollment_uma.h"
 
 #include "base/logging.h"
-#include "base/metrics/sparse_histogram.h"
+#include "base/metrics/histogram_macros.h"
 
 namespace {
 
 const char * const kMetricEnrollment = "Enterprise.Enrollment";
 const char * const kMetricEnrollmentForced = "Enterprise.EnrollmentForced";
 const char * const kMetricEnrollmentRecovery = "Enterprise.EnrollmentRecovery";
 
 }  // namespace
 
 namespace chromeos {
@@ skipping 16 matching lines @@
     case policy::EnrollmentConfig::MODE_RECOVERY:
       UMA_HISTOGRAM_SPARSE_SLOWLY(kMetricEnrollmentRecovery, sample);
       break;
     case policy::EnrollmentConfig::MODE_NONE:
       NOTREACHED();
       break;
   }
 }
 
 }  // namespace chromeos