Migrate chrome/browser files to histogram_macros.h includes.

chrome/browser/net/resource_prefetch_predictor_observer.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/net/resource_prefetch_predictor_observer.h"
 
 #include <string>
 
-#include "base/metrics/histogram.h"
+#include "base/metrics/histogram_macros.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/render_frame_host.h"
 #include "content/public/browser/resource_request_info.h"
 #include "net/url_request/url_request.h"
 #include "url/gurl.h"
 
 using content::BrowserThread;
 using predictors::ResourcePrefetchPredictor;
 
 namespace {
@@ skipping 143 matching lines @@
                  summary));
 
   ReportRequestStats(REQUEST_STATS_TOTAL_PROCESSED_RESPONSES);
   if (request_info &&
       request_info->GetResourceType() == content::RESOURCE_TYPE_MAIN_FRAME) {
     ReportMainFrameRequestStats(MAIN_FRAME_REQUEST_STATS_PROCESSED_RESPONSES);
   }
 }
 
 }  // namespace chrome_browser_net