fix: Pickup registrar for plugin by plugin registrar manager (flutter-webrtc#1752)

Co-authored-by: CloudWebRTC <duanweiwei1982@gmail.com>

Author: 2 people

windows/flutter_webrtc_plugin.cc

@@ -4,6 +4,8 @@
 #include "flutter_webrtc.h"
 #include "task_runner_windows.h"
 
+#include <flutter/plugin_registrar_windows.h>
+
 const char* kChannelName = "FlutterWebRTC.Method";
 
 namespace flutter_webrtc_plugin {
@@ -71,7 +73,7 @@ class FlutterWebRTCPluginImpl : public FlutterWebRTCPlugin {
 
 void FlutterWebRTCPluginRegisterWithRegistrar(
     FlutterDesktopPluginRegistrarRef registrar) {
-    static auto* plugin_registrar = new flutter::PluginRegistrar(registrar);
-    flutter_webrtc_plugin::FlutterWebRTCPluginImpl::RegisterWithRegistrar(
-        plugin_registrar);
+  flutter_webrtc_plugin::FlutterWebRTCPluginImpl::RegisterWithRegistrar(
+      flutter::PluginRegistrarManager::GetInstance()
+          ->GetRegistrar<flutter::PluginRegistrarWindows>(registrar));
 }