Add getGlobalPolicy to networkingPrivate API.

extensions/browser/api/networking_private/networking_private_linux.cc

Index: extensions/browser/api/networking_private/networking_private_linux.cc
diff --git a/extensions/browser/api/networking_private/networking_private_linux.cc b/extensions/browser/api/networking_private/networking_private_linux.cc
index c6a467f7b8e2631f4d1ea617f83d0c91854e247e..38f035329be0d2d62e0f509c81fa460b72f4ef3d 100644
--- a/extensions/browser/api/networking_private/networking_private_linux.cc
+++ b/extensions/browser/api/networking_private/networking_private_linux.cc
@@ -9,6 +9,7 @@
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/callback.h"
+#include "base/memory/ptr_util.h"
 #include "base/message_loop/message_loop.h"
 #include "base/strings/string16.h"
 #include "base/strings/string_split.h"
@@ -589,6 +590,11 @@ NetworkingPrivateLinux::GetDeviceStateList() {
   return device_state_list;
 }
 
+std::unique_ptr<base::DictionaryValue>
+NetworkingPrivateLinux::GetGlobalPolicy() {
+  return base::MakeUnique<base::DictionaryValue>();
+}
+
 bool NetworkingPrivateLinux::EnableNetworkType(const std::string& type) {
   return false;
 }