SystemMonitor: Move NetworkStatisticsWidget into namespace + register it

We don't want to clobber the global namespace with registered widgets.

Userland/Applications/SystemMonitor/NetworkStatisticsWidget.cpp

@@ -13,6 +13,10 @@
 #include <LibGUI/TableView.h>
 #include <LibGfx/Painter.h>
 
+REGISTER_WIDGET(SystemMonitor, NetworkStatisticsWidget)
+
+namespace SystemMonitor {
+
 NetworkStatisticsWidget::NetworkStatisticsWidget()
 {
     on_first_show = [this](auto&) {
@@ -118,3 +122,5 @@ void NetworkStatisticsWidget::update_models()
     m_tcp_socket_model->update();
     m_udp_socket_model->update();
 }
+
+}

Userland/Applications/SystemMonitor/NetworkStatisticsWidget.h

@@ -10,6 +10,8 @@
 #include <LibCore/Timer.h>
 #include <LibGUI/LazyWidget.h>
 
+namespace SystemMonitor {
+
 class NetworkStatisticsWidget final : public GUI::LazyWidget {
     C_OBJECT(NetworkStatisticsWidget)
 public:
@@ -30,3 +32,5 @@ private:
     RefPtr<Gfx::Bitmap> m_network_disconnected_bitmap;
     RefPtr<Gfx::Bitmap> m_network_link_down_bitmap;
 };
+
+}

Userland/Applications/SystemMonitor/main.cpp

@@ -175,7 +175,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     storage_widget->set_title("Storage");
     tabwidget.add_widget(storage_widget);
 
-    auto network_stats_widget = NetworkStatisticsWidget::construct();
+    auto network_stats_widget = SystemMonitor::NetworkStatisticsWidget::construct();
     network_stats_widget->set_title("Network");
     tabwidget.add_widget(network_stats_widget);