Introduce networking.cast API

extensions/browser/api/extensions_api_client.cc

Index: extensions/browser/api/extensions_api_client.cc
diff --git a/extensions/browser/api/extensions_api_client.cc b/extensions/browser/api/extensions_api_client.cc
index b9cb0756f180c9c89447be272ff43c50b4ba04e9..fa6d1c1bdf069925dd6847beeb4e91f4505673c8 100644
--- a/extensions/browser/api/extensions_api_client.cc
+++ b/extensions/browser/api/extensions_api_client.cc
@@ -103,6 +103,10 @@ MetricsPrivateDelegate* ExtensionsAPIClient::GetMetricsPrivateDelegate() {
   return nullptr;
 }
 
+NetworkingCastDelegate* ExtensionsAPIClient::GetNetworkingCastDelegate() {
+  return nullptr;
+}
+
 #if defined(OS_CHROMEOS)
 NonNativeFileSystemDelegate*
 ExtensionsAPIClient::GetNonNativeFileSystemDelegate() {