Introduce ui::PaintRecorder and use it for CursorWindowDelegate.

cc/resources/drawing_display_item.h

Index: cc/resources/drawing_display_item.h
diff --git a/cc/resources/drawing_display_item.h b/cc/resources/drawing_display_item.h
index b45a0392ad0756ef3a45212106dbcbb2cac8c13c..6edcfa51b8043aab918bfcd4435d8af961f1f70f 100644
--- a/cc/resources/drawing_display_item.h
+++ b/cc/resources/drawing_display_item.h
@@ -26,6 +26,10 @@ class CC_EXPORT DrawingDisplayItem : public DisplayItem {
     return make_scoped_ptr(new DrawingDisplayItem(picture));
   }
 
+  scoped_ptr<DrawingDisplayItem> Clone() const {
+    return make_scoped_ptr(new DrawingDisplayItem(picture_));
+  }
+
   void Raster(SkCanvas* canvas, SkDrawPictureCallback* callback) const override;
   void RasterForTracing(SkCanvas* canvas) const override;