[cluttermm] Canvas: Derive from Content.

[Murray Cumming <murrayc src gnome org>]

commit ae4404eb0d44d99cd64d2c3f276006b8d7babf25
Author: Murray Cumming <murrayc murrayc com>
Date:   Wed Sep 16 14:01:52 2015 +0200

    Canvas: Derive from Content.
    
    We already used _IMPLEMENTS_INTERFACE() but forgot to do this.
    The move constructor generated by the recent gmmproc caused a
    compiler error because of this, which is nice.

 clutter/src/canvas.hg |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)
---
diff --git a/clutter/src/canvas.hg b/clutter/src/canvas.hg
index 34abb50..2dd565c 100644
--- a/clutter/src/canvas.hg
+++ b/clutter/src/canvas.hg
@@ -28,7 +28,9 @@ namespace Clutter
 {
 
 
-class Canvas : public Glib::Object
+class Canvas
+: public Glib::Object,
+  public Content
 {
   _CLASS_GOBJECT(Canvas, ClutterCanvas, CLUTTER_CANVAS, Glib::Object, GObject)
   _IMPLEMENTS_INTERFACE(Content)