x11: Add X11 color manager subclass

This is used as part of the X11 backend to updated X11 root window
properties according to the ICC Profiles in X Specification.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2166>

src/tests/meta-backend-test.c

@@ -21,6 +21,7 @@
 
 #include "tests/meta-backend-test.h"
 
+#include "backends/meta-color-manager.h"
 #include "tests/meta-gpu-test.h"
 #include "tests/meta-monitor-manager-test.h"
 
@@ -76,6 +77,14 @@ meta_backend_test_create_monitor_manager (MetaBackend *backend,
                        NULL);
 }
 
+static MetaColorManager *
+meta_backend_test_create_color_manager (MetaBackend *backend)
+{
+  return g_object_new (META_TYPE_COLOR_MANAGER,
+                       "backend", backend,
+                       NULL);
+}
+
 ClutterInputDevice *
 meta_backend_test_add_test_device (MetaBackendTest        *backend_test,
                                    const char             *name,
@@ -183,6 +192,7 @@ meta_backend_test_class_init (MetaBackendTestClass *klass)
     META_BACKEND_X11_NESTED_CLASS (klass);
 
   backend_class->create_monitor_manager = meta_backend_test_create_monitor_manager;
+  backend_class->create_color_manager = meta_backend_test_create_color_manager;
   backend_class->is_lid_closed = meta_backend_test_is_lid_closed;
 
   backend_x11_nested_class->init_gpus = meta_backend_test_init_gpus;