Move IOThread::LoggingNetworkChangeObserver to net/base

chrome/browser/io_thread.h

Index: chrome/browser/io_thread.h
diff --git a/chrome/browser/io_thread.h b/chrome/browser/io_thread.h
index 9dad42fe17928da7a8e928acb5968d042945c6b0..1b4835943fcb2674352621c8fae6eef7c9e4174f 100644
--- a/chrome/browser/io_thread.h
+++ b/chrome/browser/io_thread.h
@@ -74,6 +74,7 @@ class HttpAuthPreferences;
 class HttpServerProperties;
 class HttpTransactionFactory;
 class HttpUserAgentSettings;
+class LoggingNetworkChangeObserver;
 class NetworkDelegate;
 class NetworkQualityEstimator;
 class ProxyConfigService;
@@ -519,8 +520,7 @@ class IOThread : public content::BrowserThreadDelegate {
   NetworkSessionConfigurator network_session_configurator_;
 
   // Observer that logs network changes to the ChromeNetLog.
-  class LoggingNetworkChangeObserver;
-  std::unique_ptr<LoggingNetworkChangeObserver> network_change_observer_;
+  std::unique_ptr<net::LoggingNetworkChangeObserver> network_change_observer_;
 
   BooleanPrefMember system_enable_referrers_;