CC Animations: Establish AnimationHost, AnimationTimeline and AnimationPlayer

cc/trees/layer_tree_impl.cc

 // Copyright 2011 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/trees/layer_tree_impl.h"
 
 #include <algorithm>
 #include <limits>
 #include <set>
 
@@ skipping 679 matching lines @@
 
 gfx::Size LayerTreeImpl::ScrollableSize() const {
   LayerImpl* root_scroll_layer = OuterViewportScrollLayer()
                                      ? OuterViewportScrollLayer()
                                      : InnerViewportScrollLayer();
   if (!root_scroll_layer || root_scroll_layer->children().empty())
     return gfx::Size();
   return root_scroll_layer->children()[0]->bounds();
 }
 
-LayerImpl* LayerTreeImpl::LayerById(int id) {
-  LayerIdMap::iterator iter = layer_id_map_.find(id);
+LayerImpl* LayerTreeImpl::LayerById(int id) const {
+  LayerIdMap::const_iterator iter = layer_id_map_.find(id);
   return iter != layer_id_map_.end() ? iter->second : NULL;
 }
 
 void LayerTreeImpl::RegisterLayer(LayerImpl* layer) {
   DCHECK(!LayerById(layer->id()));
   layer_id_map_[layer->id()] = layer;
 }
 
 void LayerTreeImpl::UnregisterLayer(LayerImpl* layer) {
   DCHECK(LayerById(layer->id()));
@@ skipping 909 matching lines @@
     scoped_ptr<PendingPageScaleAnimation> pending_animation) {
   pending_page_scale_animation_ = pending_animation.Pass();
 }
 
 scoped_ptr<PendingPageScaleAnimation>
     LayerTreeImpl::TakePendingPageScaleAnimation() {
   return pending_page_scale_animation_.Pass();
 }
 
 }  // namespace cc