Refactor PPB_NetworkMonitor_Private interface to use CompletionCallback.

ppapi/thunk/ppb_network_monitor_private_api.h

Index: ppapi/thunk/ppb_network_monitor_private_api.h
diff --git a/ppapi/thunk/ppb_network_monitor_private_api.h b/ppapi/thunk/ppb_network_monitor_private_api.h
index 124f6446c2205ccdb6ddb641ebbbc4c6cc1956a0..ec63d0adf6f3951a1b7f069f0d7d771212710d0a 100644
--- a/ppapi/thunk/ppb_network_monitor_private_api.h
+++ b/ppapi/thunk/ppb_network_monitor_private_api.h
@@ -9,11 +9,18 @@
 #include "ppapi/thunk/ppapi_thunk_export.h"
 
 namespace ppapi {
+
+class TrackedCallback;
+
 namespace thunk {
 
 class PPAPI_THUNK_EXPORT PPB_NetworkMonitor_Private_API {
  public:
   virtual ~PPB_NetworkMonitor_Private_API() {}
+
+  virtual int32_t UpdateNetworkList(
+        PP_Resource* network_list,
+        scoped_refptr<TrackedCallback> callback) = 0;
 };
 
 }  // namespace thunk