Migrate content/ files to histogram_macros.h includes.

content/browser/histogram_internals_request_job.cc

 // Copyright (c) 2012 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 "content/browser/histogram_internals_request_job.h"
 
-#include "base/metrics/histogram.h"
+#include "base/metrics/histogram_macros.h"
 #include "base/metrics/statistics_recorder.h"
 #include "content/browser/histogram_synchronizer.h"
 #include "net/base/escape.h"
 #include "net/base/net_errors.h"
 #include "net/url_request/url_request.h"
 #include "url/gurl.h"
 
 namespace content {
 
 HistogramInternalsRequestJob::HistogramInternalsRequestJob(
@@ skipping 43 matching lines @@
     const net::CompletionCallback& callback) const {
   mime_type->assign("text/html");
   charset->assign("UTF8");
 
   data->clear();
   AboutHistogram(data, path_);
   return net::OK;
 }
 
 }  // namespace content