gdk/surface: Allow inhibit layout from backend

If compute_size() returns TRUE, the layout will not be propagated to
GTK. This will be used by the X11 backend to queue asynchronous resizes
that shouldn't yet allocate in GTK.

gdk/gdksurface.c

@@ -1340,7 +1340,10 @@ gdk_surface_layout_on_clock (GdkFrameClock *clock,
 
   class = GDK_SURFACE_GET_CLASS (surface);
   if (class->compute_size)
-    class->compute_size (surface);
+    {
+      if (class->compute_size (surface))
+        return;
+    }
 
   g_signal_emit (surface, signals[LAYOUT], 0, surface->width, surface->height);
 }

gdk/gdksurfaceprivate.h

@@ -162,7 +162,7 @@ struct _GdkSurfaceClass
                                            GdkGLContext   *share,
                                            GError        **error);
   void         (* request_layout)         (GdkSurface     *surface);
-  void         (* compute_size)           (GdkSurface     *surface);
+  gboolean     (* compute_size)           (GdkSurface     *surface);
 };
 
 #define GDK_SURFACE_DESTROYED(d) (((GdkSurface *)(d))->destroyed)

gdk/wayland/gdksurface-wayland.c

@@ -639,7 +639,7 @@ configure_drag_surface_geometry (GdkSurface *surface)
                               impl->scale);
 }
 
-static void
+static gboolean
 gdk_wayland_surface_compute_size (GdkSurface *surface)
 {
   GdkWaylandSurface *impl = GDK_WAYLAND_SURFACE (surface);
@@ -655,6 +655,8 @@ gdk_wayland_surface_compute_size (GdkSurface *surface)
 
       impl->next_layout.surface_geometry_dirty = FALSE;
     }
+
+  return FALSE;
 }
 
 static void

gdk/x11/gdksurface-x11.c

@@ -295,7 +295,7 @@ gdk_x11_surface_request_layout (GdkSurface *surface)
     }
 }
 
-static void
+static gboolean
 gdk_x11_surface_compute_size (GdkSurface *surface)
 {
   GdkX11Surface *impl = GDK_X11_SURFACE (surface);
@@ -352,6 +352,8 @@ gdk_x11_surface_compute_size (GdkSurface *surface)
 
       impl->next_layout.surface_geometry_dirty = FALSE;
     }
+
+  return surface->resize_count > 0;
 }
 
 gboolean