[Chromecast] Add connectivity checking for Chromecast.

chromecast/net/net_switches.cc

Index: chromecast/net/net_switches.cc
diff --git a/components/web_resource/web_resource_switches.cc b/chromecast/net/net_switches.cc
similarity index 51%
copy from components/web_resource/web_resource_switches.cc
copy to chromecast/net/net_switches.cc
index 8a1f9a772c0997b747f3dadfd6ffdcac8bbc2cff..87f79b6827b13e0691b333581f785100de60bad9 100644
--- a/components/web_resource/web_resource_switches.cc
+++ b/chromecast/net/net_switches.cc
@@ -2,11 +2,12 @@
 // 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"
+#include "chromecast/net/net_switches.h"
 
 namespace switches {
 
-// Specifies a custom URL for fetching NTP promo data.
-const char kPromoServerURL[] = "promo-server-url";
+// Url for network connectivity checking. Default is
+// "https://clients3.google.com/generate_204".
+const char kConnectivityCheckUrl[] = "connectivity-check-url";
 
 }  // namespace switches