Migrate more files to histogram_macros.h from histogram.h.

google_apis/gcm/engine/gcm_registration_request_handler.cc

 // Copyright 2015 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 "google_apis/gcm/engine/gcm_registration_request_handler.h"
 
-#include "base/metrics/histogram.h"
+#include "base/metrics/histogram_macros.h"
 #include "google_apis/gcm/base/gcm_util.h"
 
 namespace gcm {
 
 namespace {
 
 // Request constants.
 const char kSenderKey[] = "sender";
 
 }  // namespace
@@ skipping 19 matching lines @@
 
   // Other UMAs are only reported when the request succeeds.
   if (status != RegistrationRequest::SUCCESS)
     return;
 
   UMA_HISTOGRAM_COUNTS("GCM.RegistrationRetryCount", retry_count);
   UMA_HISTOGRAM_TIMES("GCM.RegistrationCompleteTime", complete_time);
 }
 
 }  // namespace gcm