Decouple Canvas from DisplayList and map Picture and PictureRecorder more directly to their Skia co…

sky/engine/core/painting/PictureRecorder.idl

Index: sky/engine/core/painting/PictureRecorder.idl
diff --git a/sky/engine/core/painting/PictureRecorder.idl b/sky/engine/core/painting/PictureRecorder.idl
index b1ea18510b980135bc66694d42e9bd76c926f779..29d45ef47ea81d6e4465bd4f1f9a044fabab3688 100644
--- a/sky/engine/core/painting/PictureRecorder.idl
+++ b/sky/engine/core/painting/PictureRecorder.idl
@@ -2,7 +2,10 @@
 // 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 {
+  Constructor()
+] interface PictureRecorder {
+  readonly attribute boolean isRecording;
+  Canvas beginRecording(double width, double height);
   Picture endRecording();
+  void setCanvas(Canvas canvas);

[Hixie, 2015/06/20 00:44:52]

Exposing setCanvas() to dart seems really dodgy to me. What if people call it
with random Canvas objects? Or even objects that implement Canvas but aren't
actually Canvases?

[abarth-chromium, 2015/06/20 00:50:29]

This API doesn't make sense.  We should find another way to solve whatever
problem this is solving.

 };