app: implement GimpColorManaged in GimpDrawable

so now all drawables have a profile. Default to the babl format's
bultin profile and override to use the image's format in GimpLayer.

app/core/gimpdrawable.c

@@ -72,7 +72,8 @@ enum
 
 /*  local function prototypes  */
 
-static void  gimp_drawable_pickable_iface_init (GimpPickableInterface *iface);
+static void       gimp_color_managed_iface_init    (GimpColorManagedInterface *iface);
+static void       gimp_pickable_iface_init         (GimpPickableInterface     *iface);
 
 static void       gimp_drawable_dispose            (GObject           *object);
 static void       gimp_drawable_finalize           (GObject           *object);
@@ -130,6 +131,13 @@ static void       gimp_drawable_transform          (GimpItem          *item,
                                                     GimpTransformResize clip_result,
                                                     GimpProgress      *progress);
 
+static const guint8 *
+                  gimp_drawable_get_icc_profile    (GimpColorManaged  *managed,
+                                                    gsize             *len);
+static GimpColorProfile *
+                  gimp_drawable_get_color_profile  (GimpColorManaged  *managed);
+static void       gimp_drawable_profile_changed    (GimpColorManaged  *managed);
+
 static gboolean   gimp_drawable_get_pixel_at       (GimpPickable      *pickable,
                                                     gint               x,
                                                     gint               y,
@@ -196,8 +204,10 @@ static void       gimp_drawable_fs_update          (GimpLayer         *fs,
 
 
 G_DEFINE_TYPE_WITH_CODE (GimpDrawable, gimp_drawable, GIMP_TYPE_ITEM,
+                         G_IMPLEMENT_INTERFACE (GIMP_TYPE_COLOR_MANAGED,
+                                                gimp_color_managed_iface_init)
                          G_IMPLEMENT_INTERFACE (GIMP_TYPE_PICKABLE,
-                                                gimp_drawable_pickable_iface_init))
+                                                gimp_pickable_iface_init))
 
 #define parent_class gimp_drawable_parent_class
 
@@ -289,7 +299,15 @@ gimp_drawable_init (GimpDrawable *drawable)
 /* sorry for the evil casts */
 
 static void
-gimp_drawable_pickable_iface_init (GimpPickableInterface *iface)
+gimp_color_managed_iface_init (GimpColorManagedInterface *iface)
+{
+  iface->get_icc_profile   = gimp_drawable_get_icc_profile;
+  iface->get_color_profile = gimp_drawable_get_color_profile;
+  iface->profile_changed   = gimp_drawable_profile_changed;
+}
+
+static void
+gimp_pickable_iface_init (GimpPickableInterface *iface)
 {
   iface->get_image             = (GimpImage     * (*) (GimpPickable *pickable)) gimp_item_get_image;
   iface->get_format            = (const Babl    * (*) (GimpPickable *pickable)) gimp_drawable_get_format;
@@ -714,6 +732,29 @@ gimp_drawable_transform (GimpItem               *item,
     }
 }
 
+static const guint8 *
+gimp_drawable_get_icc_profile (GimpColorManaged *managed,
+                               gsize            *len)
+{
+  GimpColorProfile *profile = gimp_color_managed_get_color_profile (managed);
+
+  return gimp_color_profile_get_icc_profile (profile, len);
+}
+
+static GimpColorProfile *
+gimp_drawable_get_color_profile (GimpColorManaged *managed)
+{
+  const Babl *format = gimp_drawable_get_format (GIMP_DRAWABLE (managed));
+
+  return gimp_babl_format_get_color_profile (format);
+}
+
+static void
+gimp_drawable_profile_changed (GimpColorManaged *managed)
+{
+  gimp_viewable_invalidate_preview (GIMP_VIEWABLE (managed));
+}
+
 static gboolean
 gimp_drawable_get_pixel_at (GimpPickable *pickable,
                             gint          x,

app/core/gimplayer.c

@@ -188,12 +188,8 @@ static void    gimp_layer_set_buffer            (GimpDrawable       *drawable,
                                                  gint                offset_x,
                                                  gint                offset_y);
 
-static const guint8 *
-               gimp_layer_get_icc_profile       (GimpColorManaged   *managed,
-                                                 gsize              *len);
 static GimpColorProfile *
                gimp_layer_get_color_profile     (GimpColorManaged   *managed);
-static void    gimp_layer_profile_changed       (GimpColorManaged   *managed);
 
 static gdouble gimp_layer_get_opacity_at        (GimpPickable       *pickable,
                                                  gint                x,
@@ -407,9 +403,7 @@ gimp_layer_init (GimpLayer *layer)
 static void
 gimp_color_managed_iface_init (GimpColorManagedInterface *iface)
 {
-  iface->get_icc_profile   = gimp_layer_get_icc_profile;
   iface->get_color_profile = gimp_layer_get_color_profile;
-  iface->profile_changed   = gimp_layer_profile_changed;
 }
 
 static void
@@ -1217,15 +1211,6 @@ gimp_layer_set_buffer (GimpDrawable *drawable,
     }
 }
 
-static const guint8 *
-gimp_layer_get_icc_profile (GimpColorManaged *managed,
-                            gsize            *len)
-{
-  GimpImage *image = gimp_item_get_image (GIMP_ITEM (managed));
-
-  return gimp_color_managed_get_icc_profile (GIMP_COLOR_MANAGED (image), len);
-}
-
 static GimpColorProfile *
 gimp_layer_get_color_profile (GimpColorManaged *managed)
 {
@@ -1234,12 +1219,6 @@ gimp_layer_get_color_profile (GimpColorManaged *managed)
   return gimp_color_managed_get_color_profile (GIMP_COLOR_MANAGED (image));
 }
 
-static void
-gimp_layer_profile_changed (GimpColorManaged *managed)
-{
-  gimp_viewable_invalidate_preview (GIMP_VIEWABLE (managed));
-}
-
 static gdouble
 gimp_layer_get_opacity_at (GimpPickable *pickable,
                            gint          x,