window: Delegate model creation to CcApplication

In order be able to modify panel information statically,
we need to have access to the CcShellModel from static
functions. CcApplication, thus, is a better place for the
model to live, since we can access it outside any scope
using g_application_get_default().

It also makes sense from the modeling point of view, since
the model is not tied to the shell anymore.

shell/cc-application.c

@@ -39,6 +39,8 @@ struct _CcApplication
 {
   GtkApplication  parent;
 
+  CcShellModel   *model;
+
   CcWindow       *window;
 };
 
@@ -259,7 +261,8 @@ cc_application_startup (GApplication *application)
   gtk_application_set_accels_for_action (GTK_APPLICATION (application),
                                          "app.help", help_accels);
 
-  self->window = cc_window_new (GTK_APPLICATION (application));
+  self->model = cc_shell_model_new ();
+  self->window = cc_window_new (GTK_APPLICATION (application), self->model);
 }
 
 static void
@@ -320,3 +323,11 @@ cc_application_new (void)
                        "flags", G_APPLICATION_HANDLES_COMMAND_LINE,
                        NULL);
 }
+
+CcShellModel *
+cc_application_get_model (CcApplication *self)
+{
+  g_return_val_if_fail (CC_IS_APPLICATION (self), NULL);
+
+  return self->model;
+}