cc: Add const versions of operator* to layer iterators.

cc/layers/picture_layer_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 "cc/layers/picture_layer_impl.h"
 
 #include <algorithm>
 #include <limits>
 
 #include "base/time/time.h"
@@ skipping 1490 matching lines @@
 Tile* PictureLayerImpl::LayerRasterTileIterator::operator*() {
   DCHECK(*this);
 
   IteratorType index = stages_[current_stage_].iterator_type;
   DCHECK(iterators_[index]);
   DCHECK(iterators_[index].get_type() == stages_[current_stage_].tile_type);
 
   return *iterators_[index];
 }
 
+const Tile* PictureLayerImpl::LayerRasterTileIterator::operator*() const {
+  DCHECK(*this);
+
+  IteratorType index = stages_[current_stage_].iterator_type;
+  DCHECK(iterators_[index]);
+  DCHECK(iterators_[index].get_type() == stages_[current_stage_].tile_type);
+
+  return *iterators_[index];
+}
+
 PictureLayerImpl::LayerEvictionTileIterator::LayerEvictionTileIterator()
     : iterator_index_(0),
       iteration_stage_(TilePriority::EVENTUALLY),
       required_for_activation_(false),
       layer_(NULL) {}
 
 PictureLayerImpl::LayerEvictionTileIterator::LayerEvictionTileIterator(
     PictureLayerImpl* layer,
     TreePriority tree_priority)
     : iterator_index_(0),
@@ skipping 57 matching lines @@
   }
 }
 
 PictureLayerImpl::LayerEvictionTileIterator::~LayerEvictionTileIterator() {}
 
 Tile* PictureLayerImpl::LayerEvictionTileIterator::operator*() {
   DCHECK(*this);
   return *iterators_[iterator_index_];
 }
 
+const Tile* PictureLayerImpl::LayerEvictionTileIterator::operator*() const {
+  DCHECK(*this);
+  return *iterators_[iterator_index_];
+}
+
 PictureLayerImpl::LayerEvictionTileIterator&
 PictureLayerImpl::LayerEvictionTileIterator::
 operator++() {
   DCHECK(*this);
   ++iterators_[iterator_index_];
   if (!iterators_[iterator_index_] ||
       !IsCorrectType(&iterators_[iterator_index_])) {
     AdvanceToNextIterator();
   }
   return *this;
@@ skipping 31 matching lines @@
   return iterator_index_ < iterators_.size();
 }
 
 bool PictureLayerImpl::LayerEvictionTileIterator::IsCorrectType(
     PictureLayerTiling::TilingEvictionTileIterator* it) const {
   return it->get_type() == iteration_stage_ &&
          (**it)->required_for_activation() == required_for_activation_;
 }
 
 }  // namespace cc