Explicitly create per backend stage windows

Split the stage window implementations into three separate objects: one
for X11 as a compositing manager, one for X11 running as a nested
Wayland compositor, and one for running with the native backend.

The new stage window implementations are only thin shells; this is in
preparation for making the stage windows behave more differently.

https://bugzilla.gnome.org/show_bug.cgi?id=768976

src/backends/native/meta-clutter-backend-native.c

@@ -29,6 +29,7 @@
 #include "backends/meta-backend-private.h"
 #include "backends/meta-renderer.h"
 #include "backends/native/meta-clutter-backend-native.h"
+#include "backends/native/meta-stage-native.h"
 #include "clutter/clutter.h"
 #include "meta/meta-backend.h"
 
@@ -50,6 +51,17 @@ meta_clutter_backend_native_get_renderer (ClutterBackend  *clutter_backend,
   return meta_renderer_create_cogl_renderer (renderer);
 }
 
+static ClutterStageWindow *
+meta_clutter_backend_native_create_stage (ClutterBackend  *backend,
+                                          ClutterStage    *wrapper,
+                                          GError         **error)
+{
+  return g_object_new (META_TYPE_STAGE_NATIVE,
+                       "backend", backend,
+                       "wrapper", wrapper,
+                       NULL);
+}
+
 static void
 meta_clutter_backend_native_init (MetaClutterBackendNative *clutter_backend_nativen)
 {
@@ -61,4 +73,5 @@ meta_clutter_backend_native_class_init (MetaClutterBackendNativeClass *klass)
   ClutterBackendClass *clutter_backend_class = CLUTTER_BACKEND_CLASS (klass);
 
   clutter_backend_class->get_renderer = meta_clutter_backend_native_get_renderer;
+  clutter_backend_class->create_stage = meta_clutter_backend_native_create_stage;
 }

src/backends/native/meta-stage-native.c

@@ -0,0 +1,45 @@
+/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */
+
+/*
+ * Copyright (C) 2016 Red Hat Inc.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
+ * 02111-1307, USA.
+ *
+ * Written by:
+ *     Jonas Ådahl <jadahl@gmail.com>
+ */
+
+#include "config.h"
+
+#include "backends/native/meta-stage-native.h"
+
+struct _MetaStageNative
+{
+  ClutterStageEglNative parent;
+};
+
+G_DEFINE_TYPE (MetaStageNative, meta_stage_native,
+               CLUTTER_TYPE_STAGE_EGL_NATIVE)
+
+static void
+meta_stage_native_init (MetaStageNative *stage_native)
+{
+}
+
+static void
+meta_stage_native_class_init (MetaStageNativeClass *klass)
+{
+}

src/backends/native/meta-stage-native.h

@@ -0,0 +1,34 @@
+/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */
+
+/*
+ * Copyright (C) 2016 Red Hat Inc.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
+ * 02111-1307, USA.
+ *
+ * Written by:
+ *     Jonas Ådahl <jadahl@gmail.com>
+ */
+
+#ifndef META_STAGE_NATIVE_H
+#define META_STAGE_NATIVE_H
+
+#include "clutter/clutter-mutter.h"
+
+#define META_TYPE_STAGE_NATIVE (meta_stage_native_get_type ())
+G_DECLARE_FINAL_TYPE (MetaStageNative, meta_stage_native,
+                      META, STAGE_NATIVE, ClutterStageEglNative)
+
+#endif /* META_STAGE_NATIVE_H */