Update Linux template app to pass through command line arguments to the Dart entrypoint (#68535)

packages/flutter_tools/templates/app/linux.tmpl/my_application.cc.tmpl

@@ -9,12 +9,14 @@
 
 struct _MyApplication {
   GtkApplication parent_instance;
+  char** dart_entrypoint_arguments;
 };
 
 G_DEFINE_TYPE(MyApplication, my_application, GTK_TYPE_APPLICATION)
 
 // Implements GApplication::activate.
 static void my_application_activate(GApplication* application) {
+  MyApplication* self = MY_APPLICATION(application);
   GtkWindow* window =
       GTK_WINDOW(gtk_application_window_new(GTK_APPLICATION(application)));
 
@@ -50,6 +52,7 @@ static void my_application_activate(GApplication* application) {
   gtk_widget_show(GTK_WIDGET(window));
 
   g_autoptr(FlDartProject) project = fl_dart_project_new();
+  fl_dart_project_set_dart_entrypoint_arguments(project, self->dart_entrypoint_arguments);
 
   FlView* view = fl_view_new(project);
   gtk_widget_show(GTK_WIDGET(view));
@@ -60,8 +63,36 @@ static void my_application_activate(GApplication* application) {
   gtk_widget_grab_focus(GTK_WIDGET(view));
 }
 
+// Implements GApplication::local_command_line.
+static gboolean my_application_local_command_line(GApplication* application, gchar ***arguments, int *exit_status) {
+  MyApplication* self = MY_APPLICATION(application);
+  // Strip out the first argument as it is the binary name.
+  self->dart_entrypoint_arguments = g_strdupv(*arguments + 1);
+
+  g_autoptr(GError) error = nullptr;
+  if (!g_application_register(application, nullptr, &error)) {
+     g_warning("Failed to register: %s", error->message);
+     *exit_status = 1;
+     return TRUE;
+  }
+
+  g_application_activate(application);
+  *exit_status = 0;
+
+  return TRUE;
+}
+
+// Implements GObject::dispose.
+static void my_application_dispose(GObject *object) {
+  MyApplication* self = MY_APPLICATION(object);
+  g_clear_pointer(&self->dart_entrypoint_arguments, g_strfreev);
+  G_OBJECT_CLASS(my_application_parent_class)->dispose(object);
+}
+
 static void my_application_class_init(MyApplicationClass* klass) {
   G_APPLICATION_CLASS(klass)->activate = my_application_activate;
+  G_APPLICATION_CLASS(klass)->local_command_line = my_application_local_command_line;
+  G_OBJECT_CLASS(klass)->dispose = my_application_dispose;
 }
 
 static void my_application_init(MyApplication* self) {}