Make using WebContentsUserData simpler.

chrome/browser/tab_contents/navigation_metrics_recorder.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 "chrome/browser/tab_contents/navigation_metrics_recorder.h"
 
 #include "base/metrics/histogram.h"
 #include "content/public/browser/navigation_details.h"
 #include "content/public/browser/navigation_entry.h"
 
-int NavigationMetricsRecorder::kUserDataKey;
+DEFINE_WEB_CONTENTS_USER_DATA_KEY(NavigationMetricsRecorder)
 
 namespace {
 
 enum Scheme {
   SCHEME_UNKNOWN,
   SCHEME_HTTP,
   SCHEME_HTTPS,
   SCHEME_FILE,
   SCHEME_FTP,
   SCHEME_DATA,
@@ skipping 41 matching lines @@
 
 NavigationMetricsRecorder::~NavigationMetricsRecorder() {
 }
 
 void NavigationMetricsRecorder::DidNavigateMainFrame(
       const content::LoadCommittedDetails& details,
       const content::FrameNavigateParams& params) {
   RecordMainFrameNavigation(details);
 }