Remove unused code and exclude unused files on Chrome OS too.

net/base/network_change_notifier.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 "net/base/network_change_notifier.h"
 #include "net/base/network_change_notifier_factory.h"
 #include "build/build_config.h"
 #if defined(OS_WIN)
 #include "net/base/network_change_notifier_win.h"
-#elif defined(OS_LINUX)
+#elif defined(OS_LINUX) && !defined(OS_CHROMEOS)
 #include "net/base/network_change_notifier_linux.h"
 #elif defined(OS_MACOSX)
 #include "net/base/network_change_notifier_mac.h"
 #endif
 
 namespace net {
 
 namespace {
 
 // The actual singleton notifier.  The class contract forbids usage of the API
@@ skipping 142 matching lines @@
   DCHECK(g_network_change_notifier);
   g_network_change_notifier = NULL;
 }
 
 NetworkChangeNotifier::DisableForTest::~DisableForTest() {
   DCHECK(!g_network_change_notifier);
   g_network_change_notifier = network_change_notifier_;
 }
 
 }  // namespace net