[Chromecast] Add connectivity checking for Chromecast.

chromecast/net/net_switches.h

Index: chromecast/net/net_switches.h
diff --git a/components/web_resource/web_resource_switches.cc b/chromecast/net/net_switches.h
similarity index 56%
copy from components/web_resource/web_resource_switches.cc
copy to chromecast/net/net_switches.h
index 8a1f9a772c0997b747f3dadfd6ffdcac8bbc2cff..dda9cac54fcd8ec8e8af35565fac0a3405cf1fc2 100644
--- a/components/web_resource/web_resource_switches.cc
+++ b/chromecast/net/net_switches.h
@@ -2,11 +2,13 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "components/web_resource/web_resource_switches.h"
+#ifndef CHROMECAST_NET_NET_SWITCHES_H_
+#define CHROMECAST_NET_NET_SWITCHES_H_
 
 namespace switches {
 
-// Specifies a custom URL for fetching NTP promo data.
-const char kPromoServerURL[] = "promo-server-url";
+extern const char kConnectivityCheckUrl[];
 
 }  // namespace switches
+
+#endif  // CHROMECAST_NET_NET_SWITCHES_H_