Activate LayerImpl tree with sync+push instead of pointer swap

cc/picture_pile_impl.cc

 // Copyright 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 "base/debug/trace_event.h"
 #include "cc/picture_pile_impl.h"
 #include "cc/region.h"
 #include "cc/rendering_stats.h"
 #include "third_party/skia/include/core/SkCanvas.h"
 #include "third_party/skia/include/core/SkSize.h"
@@ skipping 81 matching lines @@
 
 void PicturePileImpl::GatherPixelRefs(
     const gfx::Rect& rect, std::list<skia::LazyPixelRef*>& pixel_refs) {
   std::list<skia::LazyPixelRef*> result;
   for (Pile::const_iterator i = pile_.begin(); i != pile_.end(); ++i) {
     (*i)->GatherPixelRefs(rect, result);
     pixel_refs.splice(pixel_refs.end(), result);
   }
 }
 
+void PicturePileImpl::PushPropertiesTo(PicturePileImpl* other) {
+  PicturePileBase::PushPropertiesTo(other);
+  other->clones_ = clones_;
+}
+
 skia::RefPtr<SkPicture> PicturePileImpl::GetFlattenedPicture() {
   TRACE_EVENT0("cc", "PicturePileImpl::GetFlattenedPicture");
 
   gfx::Rect layer_rect;
   for (Pile::const_iterator i = pile_.begin(); i != pile_.end(); ++i) {
     layer_rect.Union((*i)->LayerRect());
   }
 
   skia::RefPtr<SkPicture> picture = skia::AdoptRef(new SkPicture);
   if (layer_rect.IsEmpty())
     return picture;
 
   SkCanvas* canvas = picture->beginRecording(
       layer_rect.width(),
       layer_rect.height(),
       SkPicture::kUsePathBoundsForClip_RecordingFlag);
 
   RenderingStats stats;
   Raster(canvas, layer_rect, 1.0, &stats);
   picture->endRecording();
 
   return picture;
 }
 
 }  // namespace cc