cc: Make DisplayItemList::Append replay into an SkPicture

ui/compositor/layer.cc

 // Copyright (c) 2012 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.
 
 #include "ui/compositor/layer.h"
 
 #include <algorithm>
 
 #include "base/auto_reset.h"
 #include "base/command_line.h"
@@ skipping 737 matching lines @@
   scoped_ptr<gfx::Canvas> canvas(gfx::Canvas::CreateCanvasWithoutScaling(
       sk_canvas, device_scale_factor_));
   if (delegate_)
     delegate_->OnPaintLayer(PaintContext(canvas.get(), clip));
 }
 
 scoped_refptr<cc::DisplayItemList> Layer::PaintContentsToDisplayList(
     const gfx::Rect& clip,
     ContentLayerClient::PaintingControlSetting painting_control) {
   TRACE_EVENT1("ui", "Layer::PaintContentsToDisplayList", "name", name_);
-  scoped_refptr<cc::DisplayItemList> list = cc::DisplayItemList::Create();
+  scoped_refptr<cc::DisplayItemList> list = cc::DisplayItemList::Create(clip);

[danakj, 2015/04/14 20:49:34]

This is weird. Maybe cc should make the DisplayItemList with the clip and give
it to PaintContentsToDisplayList? Is there a reason why this returns a refptr,
does it require the ability to decide to reuse or make a new DisplayItemList?

[ajuma, 2015/04/14 21:51:27]

Done. This approach seems a lot cleaner.

   if (delegate_) {
     // TODO(danakj): Save the invalidation on the layer and pass that down
     // instead of the |clip| here. That will break everything until View
     // early-outs emit cached display items instead of nothing.
     gfx::Rect invalidation = clip;
     DCHECK(clip.Contains(invalidation));
     delegate_->OnPaintLayer(
         PaintContext(list.get(), device_scale_factor_, clip, invalidation));
   }
   return list;
@@ skipping 323 matching lines @@
       children_.end(),
       std::bind2nd(std::mem_fun(&Layer::RemoveAnimatorsInTreeFromCollection),
                    collection));
 }
 
 bool Layer::IsAnimating() const {
   return animator_.get() && animator_->is_animating();
 }
 
 }  // namespace ui