FlutterAngleTexture invoke resize callback on size change, cleanup on destruction and call glFinish in RenderCallback

FlutterAngleTexture invoke resize callback on size change, cleanup on destruction and call glFinish in RenderCallback
move OpenGlTextureBuffer cleanup to destructor

windows/polyvox_filament_plugin.h

@@ -30,7 +30,8 @@ public:
   static void RegisterWithRegistrar(flutter::PluginRegistrarWindows *registrar);
 
   PolyvoxFilamentPlugin(flutter::TextureRegistrar *textureRegistrar,
-                        flutter::PluginRegistrarWindows *registrar);
+                        flutter::PluginRegistrarWindows *registrar,
+                        std::unique_ptr<flutter::MethodChannel<flutter::EncodableValue>>& channel);
   virtual ~PolyvoxFilamentPlugin();
 
   // Disallow copy and assign.
@@ -44,6 +45,7 @@ public:
 
   flutter::PluginRegistrarWindows *_pluginRegistrar;
   flutter::TextureRegistrar *_textureRegistrar;
+  std::unique_ptr<flutter::MethodChannel<flutter::EncodableValue>> _channel;
   std::map<uint32_t, ResourceBuffer> _resources;
   std::shared_ptr<std::mutex> _renderMutex;
  
@@ -66,6 +68,7 @@ public:
     EGLConfig _eglConfig = NULL;
     EGLDisplay _eglDisplay = NULL;
     std::unique_ptr<FlutterAngleTexture> _active = nullptr;
+    std::unique_ptr<FlutterAngleTexture> _inactive = nullptr;
     ID3D11Device* _D3D11Device = nullptr;
     ID3D11DeviceContext* _D3D11DeviceContext = nullptr;
     filament::backend::Platform* _platform = nullptr;