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

sky/engine/core/painting/Canvas.idl

 // 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.
 
 // TODO(mpcomplete): Figure out a better SkMatrix representation.
-interface Canvas {
-  // Height and width are used for culling optimizations and do not necessarily
-  // imply that the Canvas is backed by a buffer with any specific bounds.
-  readonly attribute float height;
-  readonly attribute float width;
-
+[
+  Constructor(PictureRecorder recorder, double width, double height),
+  RaisesException=Constructor,
+] interface Canvas {
   void save();
   // TODO(jackson): Paint should be optional, but making it optional causes crash
   void saveLayer(Rect bounds, /* optional */ Paint paint);
   void restore();
 
   void translate(float dx, float dy);
   void scale(float sx, float sy);
   void rotate(float radians);
   void skew(float sx, float sy);
   void concat(Float32List matrix4);
 
   void clipRect(Rect rect);
   void clipRRect(RRect rrect);
   void clipPath(Path path);
 
   void drawLine(float x0, float y0, float x1, float y1, Paint paint);
   void drawPicture(Picture picture);
   void drawPaint(Paint paint);
   void drawRect(Rect rect, Paint paint);
   void drawRRect(RRect rrect, Paint paint);
   void drawOval(Rect rect, Paint paint);
   void drawCircle(float x, float y, float radius, Paint paint);
   void drawPath(Path path, Paint paint);
   void drawImage(Image image, float x, float y, Paint paint);
 };