Add an API to set the ColorFilter on a Paint object.

sky/engine/core/painting/ColorFilter.idl

Index: sky/engine/core/painting/ColorFilter.idl
diff --git a/sky/engine/core/painting/PictureRecorder.idl b/sky/engine/core/painting/ColorFilter.idl
similarity index 52%
copy from sky/engine/core/painting/PictureRecorder.idl
copy to sky/engine/core/painting/ColorFilter.idl
index b1ea18510b980135bc66694d42e9bd76c926f779..bbc51f22f814c97d4c1b87750e0031a14e9645ec 100644
--- a/sky/engine/core/painting/PictureRecorder.idl
+++ b/sky/engine/core/painting/ColorFilter.idl
@@ -1,8 +1,9 @@
 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
+
 [
-    Constructor(double width, double height)
-] interface PictureRecorder : Canvas {
-  Picture endRecording();
+  // TODO(mpcomplete): add Color and SkXfermode::Mode types.
+  Constructor(unsigned long color, unsigned long transferMode),
+] interface ColorFilter {
 };