Transmit a X-Chrome-UMA-Enabled bit to Google domains from clients that have UMA enabled.

chrome/browser/metrics/metrics_service.h

 // 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.
 
 // This file defines a service that collects information about the user
 // experience in order to help improve future versions of the app.
 
 #ifndef CHROME_BROWSER_METRICS_METRICS_SERVICE_H_
 #define CHROME_BROWSER_METRICS_METRICS_SERVICE_H_
 #pragma once
@@ skipping 14 matching lines @@
 #include "content/public/common/url_fetcher_delegate.h"
 #include "content/public/browser/notification_observer.h"
 #include "content/public/browser/notification_registrar.h"
 
 #if defined(OS_CHROMEOS)
 #include "chrome/browser/chromeos/external_metrics.h"
 #endif
 
 class BookmarkModel;
 class BookmarkNode;
+class ChromeNetworkDelegate;
 class MetricsReportingScheduler;
 class PrefService;
 class Profile;
 class TemplateURLService;
 
 namespace base {
 class DictionaryValue;
 class MessageLoopProxy;
 }
 
@@ skipping 385 matching lines @@
 };
 
 // This class limits and documents access to the IsMetricsReportingEnabled()
 // method. Since the method is private, each user has to be explicitly declared
 // as a 'friend' below.
 class MetricsServiceHelper {
  private:
   friend class InstantFieldTrial;
   friend bool prerender::IsOmniboxEnabled(Profile* profile);
   friend class extensions::ExtensionDownloader;
+  friend class ChromeNetworkDelegate;
 
   // Returns true if prefs::kMetricsReportingEnabled is set.
   static bool IsMetricsReportingEnabled();
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(MetricsServiceHelper);
 };
 
 #endif  // CHROME_BROWSER_METRICS_METRICS_SERVICE_H_