wl: Do not rely on CogShell to track viewports

Use the new CogPlatform.viewport_{created,disposed} vfuncs to track live
CogViewport instances, instead of relying on CogShell. This removes all
the usage of the shell instance in the Wayland platform, paving the way
to uncouple CogShell from CogPlatform.

platform/wayland/cog-platform-wl.c

@@ -1,5 +1,6 @@
 /*
  * cog-wl-platform.c
+ * Copyright (C) 2019-2023 Igalia S.L.
  * Copyright (C) 2018 Eduardo Lima <[email protected]>
  * Copyright (C) 2018 Adrian Perez de Castro <[email protected]>
  *
@@ -1321,18 +1322,8 @@ cog_wl_platform_on_notify_visible_view(CogWlPlatform *self, GParamSpec *pspec G_
     cog_wl_view_update_surface_contents(view);
 }
 
-static void
-cog_wl_platform_on_create_viewport(CogWlPlatform *platform, CogViewport *viewport, CogShell *shell)
-{
-    g_assert(COG_IS_VIEWPORT(viewport));
-    cog_wl_viewport_create_window(COG_WL_VIEWPORT(viewport), NULL);
-
-    g_signal_connect_object(viewport, "notify::visible-view", G_CALLBACK(cog_wl_platform_on_notify_visible_view),
-                            platform, G_CONNECT_AFTER | G_CONNECT_SWAPPED);
-}
-
 static gboolean
-cog_wl_platform_setup(CogPlatform *platform, CogShell *shell, const char *params, GError **error)
+cog_wl_platform_setup(CogPlatform *platform, CogShell *shell G_GNUC_UNUSED, const char *params, GError **error)
 {
     g_return_val_if_fail(COG_IS_SHELL(shell), FALSE);
 
@@ -1356,12 +1347,7 @@ cog_wl_platform_setup(CogPlatform *platform, CogShell *shell, const char *params
     }
 
     /* init WPE host data */
-    wpe_fdo_initialize_for_egl_display(display->egl_display);
-
-    /* get a reference to the hashmap with viewports added to the shell */
-    self->viewports = cog_shell_get_viewports(shell);
-
-    g_signal_connect_swapped(shell, "create-viewport", G_CALLBACK(cog_wl_platform_on_create_viewport), self);
+    wpe_fdo_initialize_for_egl_display(self->display->egl_display);
 
 #if COG_ENABLE_WESTON_DIRECT_DISPLAY
     wpe_video_plane_display_dmabuf_register_receiver(&video_plane_display_dmabuf_receiver, platform);
@@ -1382,6 +1368,8 @@ cog_wl_platform_finalize(GObject *object)
     clear_egl(platform->display);
     clear_wayland(platform);
 
+    g_clear_pointer(&platform->viewports, g_ptr_array_unref);
+
     G_OBJECT_CLASS(cog_wl_platform_parent_class)->finalize(object);
 }
 
@@ -1432,6 +1420,30 @@ cog_wl_platform_popup_update(void)
     cog_wl_popup_update(platform->popup);
 }
 
+static void
+cog_wl_platform_viewport_created(CogPlatform *platform, CogViewport *viewport)
+{
+    CogWlPlatform *self = COG_WL_PLATFORM(platform);
+
+    g_assert(!g_ptr_array_find(self->viewports, viewport, NULL));
+    g_ptr_array_add(self->viewports, viewport);
+
+    // TODO: Move into CogWlViewport.constructed or somewhere more suitable.
+    cog_wl_viewport_create_window(COG_WL_VIEWPORT(viewport), NULL);
+
+    g_signal_connect_object(viewport, "notify::visible-view", G_CALLBACK(cog_wl_platform_on_notify_visible_view),
+                            platform, G_CONNECT_AFTER | G_CONNECT_SWAPPED);
+}
+
+static void
+cog_wl_platform_viewport_disposed(CogPlatform *platform, CogViewport *viewport)
+{
+    CogWlPlatform *self = COG_WL_PLATFORM(platform);
+
+    gboolean removed G_GNUC_UNUSED = g_ptr_array_remove_fast(self->viewports, viewport);
+    g_assert(removed);
+}
+
 static void
 cog_wl_platform_class_init(CogWlPlatformClass *klass)
 {
@@ -1444,6 +1456,8 @@ cog_wl_platform_class_init(CogWlPlatformClass *klass)
     platform_class->get_viewport_type = cog_wl_viewport_get_type;
     platform_class->setup = cog_wl_platform_setup;
     platform_class->create_im_context = cog_wl_platform_create_im_context;
+    platform_class->viewport_created = cog_wl_platform_viewport_created;
+    platform_class->viewport_disposed = cog_wl_platform_viewport_disposed;
 }
 
 static void
@@ -1452,8 +1466,9 @@ cog_wl_platform_class_finalize(CogWlPlatformClass *klass)
 }
 
 static void
-cog_wl_platform_init(CogWlPlatform *platform)
+cog_wl_platform_init(CogWlPlatform *self)
 {
+    self->viewports = g_ptr_array_sized_new(3);
 }
 
 G_MODULE_EXPORT void