Gdk: fix wrong user_data handling in resize_cairo_surface()

Instead of destroying the surface in the backend if this is
unable to resize, let the core code do it, and do it properly.

Based on a patch by Benjamin Otte.

https://bugzilla.gnome.org/show_bug.cgi?id=725172

gdk/broadway/gdkwindow-broadway.c

@@ -365,16 +365,14 @@ _gdk_broadway_window_destroy (GdkWindow *window,
 				       impl->id);
 }
 
-static cairo_surface_t *
+static gboolean
 gdk_window_broadway_resize_cairo_surface (GdkWindow       *window,
 					  cairo_surface_t *surface,
 					  gint             width,
 					  gint             height)
 {
   /* Image surfaces cannot be resized */
-  cairo_surface_destroy (surface);
-
-  return NULL;
+  return FALSE;
 }
 
 static void

gdk/gdkoffscreenwindow.c

@@ -550,7 +550,7 @@ gdk_offscreen_window_queue_antiexpose (GdkWindow *window,
   return FALSE;
 }
 
-static cairo_surface_t *
+static gboolean
 gdk_offscreen_window_resize_cairo_surface (GdkWindow       *window,
                                            cairo_surface_t *surface,
                                            gint             width,
@@ -559,7 +559,7 @@ gdk_offscreen_window_resize_cairo_surface (GdkWindow       *window,
   /* No-op.  The surface gets resized in
    * gdk_offscreen_window_move_resize_internal().
    */
-  return surface;
+  return TRUE;
 }
 
 /**

gdk/gdkwindow.c

@@ -1003,17 +1003,17 @@ recompute_visible_regions_internal (GdkWindow *private,
 	}
     }
 
-  if (private->cairo_surface && gdk_window_has_impl (private))
+  if (private->cairo_surface)
     {
-      GdkWindowImplClass *iface = GDK_WINDOW_IMPL_GET_CLASS (private->impl);
-
-      private->cairo_surface = iface->resize_cairo_surface (private,
-                                                            private->cairo_surface,
-                                                            private->width,
-                                                            private->height);
+      if (!gdk_window_has_impl (private) ||
+          !GDK_WINDOW_IMPL_GET_CLASS (private->impl)->resize_cairo_surface (private,
+                                                                            private->cairo_surface,
+                                                                            private->width,
+                                                                            private->height))
+        {
+          gdk_window_drop_cairo_surface (private);
+        }
     }
-  else if (private->cairo_surface)
-    gdk_window_drop_cairo_surface (private);
 }
 
 /* Call this when private has changed in one or more of these ways:

gdk/gdkwindowimpl.h

@@ -158,10 +158,14 @@ struct _GdkWindowImplClass
   */
   void         (*destroy_foreign)       (GdkWindow       *window);
 
-  cairo_surface_t * (* resize_cairo_surface) (GdkWindow       *window,
-                                              cairo_surface_t *surface,
-                                              gint             width,
-                                              gint             height);
+  /* Resizes @surface to a new size. If successful, return %TRUE.
+   * If the backend cannot resize surfaces, return %FALSE and a new
+   * surface will be created instead.
+   */
+  gboolean     (* resize_cairo_surface) (GdkWindow       *window,
+                                         cairo_surface_t *surface,
+                                         gint             width,
+                                         gint             height);
 
   /* optional */
   gboolean     (* beep)                 (GdkWindow       *window);

gdk/quartz/gdkwindow-quartz.c

@@ -1104,16 +1104,14 @@ gdk_quartz_window_destroy (GdkWindow *window,
     }
 }
 
-static cairo_surface_t *
+static gboolean
 gdk_window_quartz_resize_cairo_surface (GdkWindow       *window,
                                         cairo_surface_t *surface,
                                         gint             width,
                                         gint             height)
 {
   /* Quartz surfaces cannot be resized */
-  cairo_surface_destroy (surface);
-
-  return NULL;
+  return FALSE;
 }
 
 static void

gdk/wayland/gdkwindow-wayland.c

@@ -1481,14 +1481,14 @@ gdk_window_wayland_destroy_foreign (GdkWindow *window)
 {
 }
 
-static cairo_surface_t *
+static gboolean
 gdk_window_wayland_resize_cairo_surface (GdkWindow       *window,
                                          cairo_surface_t *surface,
                                          gint             width,
                                          gint             height)
 {
   /* cairo image surfaces cannot be resized */
-  return NULL;
+  return FALSE;
 }
 
 static cairo_region_t *

gdk/win32/gdkwindow-win32.c

@@ -796,16 +796,14 @@ gdk_win32_window_destroy (GdkWindow *window,
     }
 }
 
-static cairo_surface_t *
+static gboolean
 gdk_win32_window_resize_cairo_surface (GdkWindow       *window,
                                        cairo_surface_t *surface,
                                        gint             width,
                                        gint             height)
 {
   /* XXX: Make Cairo surface use DC clip */
-  cairo_surface_destroy (surface);
-
-  return NULL;
+  return FALSE;
 }
 
 static void

gdk/x11/gdkwindow-x11.c

@@ -1337,7 +1337,7 @@ gdk_x11_window_destroy (GdkWindow *window,
     XDestroyWindow (GDK_WINDOW_XDISPLAY (window), GDK_WINDOW_XID (window));
 }
 
-static cairo_surface_t *
+static gboolean
 gdk_window_x11_resize_cairo_surface (GdkWindow       *window,
                                      cairo_surface_t *surface,
                                      gint             width,
@@ -1345,7 +1345,7 @@ gdk_window_x11_resize_cairo_surface (GdkWindow       *window,
 {
   cairo_xlib_surface_set_size (surface, width, height);
 
-  return surface;
+  return TRUE;
 }
 
 static void