[ONEMPERS-274] implemented freeMemory call support from dart (#14)

Co-authored-by: Sebastian Miasojed <[email protected]>

Author: michalkucharczyk

src/wayland_display.cc

@@ -617,6 +617,18 @@ bool WaylandDisplay::SetupEngine(const std::string &bundle_path, const std::vect
       .icu_data_path     = icu_data_path.c_str(),
       .command_line_argc = static_cast<int>(command_line_args_c.size()),
       .command_line_argv = command_line_args_c.data(),
+      .platform_message_callback = [](const FlutterPlatformMessage *message, void *data) -> void {
+	if (std::string(message->channel) == "flutter/platform" && std::string((char *)message->message).find("\"method\":\"freeMemory\"") != std::string::npos) {
+          WaylandDisplay *const wd = get_wayland_display(data);
+          if (wd->engine_) {
+            auto ret = FlutterEngineNotifyLowMemoryWarning(wd->engine_);
+            if (ret != kSuccess) {
+              dbgE("Could not handle platform message request\n");
+            }
+            FlutterEngineSendPlatformMessageResponse(wd->engine_, message->response_handle, nullptr, 0);
+          }
+        }
+      },
       .vsync_callback    = [](void *data, intptr_t baton) -> void {
         WaylandDisplay *const wd = get_wayland_display(data);