cc: Remove AsValue virtual from DisplayItem.

cc/playback/drawing_display_item.h

Index: cc/playback/drawing_display_item.h
diff --git a/cc/playback/drawing_display_item.h b/cc/playback/drawing_display_item.h
index ef5f4d57d658479735175ecfba0caa9619811f15..bd14b8fc8d63464930a8b08d476b931ed853c8a3 100644
--- a/cc/playback/drawing_display_item.h
+++ b/cc/playback/drawing_display_item.h
@@ -29,14 +29,14 @@ class CC_EXPORT DrawingDisplayItem : public DisplayItem {
 
   void Raster(SkCanvas* canvas,
               SkPicture::AbortCallback* callback) const override;
-  void AsValueInto(const gfx::Rect& visual_rect,
-                   base::trace_event::TracedValue* array) const override;
 
   size_t ExternalMemoryUsage() const;
   int ApproximateOpCount() const;
 
   void CloneTo(DrawingDisplayItem* item) const;
 
+  const PaintRecord& picture() const { return *picture_; }
+
  private:
   void SetNew(sk_sp<const PaintRecord> record);