Activate LayerImpl tree with sync+push instead of pointer swap

cc/picture_layer_tiling_set.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 "cc/picture_layer_tiling_set.h"
 
 namespace cc {
 
 namespace {
 
 class LargestToSmallestScaleFunctor {
  public:
   bool operator() (PictureLayerTiling* left, PictureLayerTiling* right) {
     return left->contents_scale() > right->contents_scale();
   }
 };
 
 }  // namespace
 
 
 PictureLayerTilingSet::PictureLayerTilingSet(
     PictureLayerTilingClient * client)
     : client_(client) {
 }
 
 PictureLayerTilingSet::~PictureLayerTilingSet() {
 }
 
+void PictureLayerTilingSet::SetClient(PictureLayerTilingClient* client) {
+  client_ = client;
+  for (size_t i = 0; i < tilings_.size(); ++i)
+    tilings_[i]->SetClient(client_);
+}
+
 void PictureLayerTilingSet::CloneAll(
     const PictureLayerTilingSet& other,
     const Region& invalidation) {
   tilings_.clear();
   tilings_.reserve(other.tilings_.size());
   for (size_t i = 0; i < other.tilings_.size(); ++i) {
     tilings_.push_back(other.tilings_[i]->Clone());
     // Intentionally use this set's layer bounds, as it may have changed.
     tilings_.back()->SetLayerBounds(layer_bounds_);
     tilings_.back()->SetClient(client_);
@@ skipping 223 matching lines @@
         time_delta);
   }
 }
 
 void PictureLayerTilingSet::DidBecomeActive() {
   for (size_t i = 0; i < tilings_.size(); ++i)
     tilings_[i]->DidBecomeActive();
 }
 
 }  // namespace cc