cc: Move LayerEvictionTileIterator to a separate file and make it a queue

cc/resources/tiling_set_eviction_queue.h

+// Copyright 2014 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.
+
+#ifndef CC_RESOURCES_TILING_SET_EVICTION_QUEUE_H_
+#define CC_RESOURCES_TILING_SET_EVICTION_QUEUE_H_
+
+#include "cc/base/cc_export.h"
+#include "cc/resources/picture_layer_tiling_set.h"
+
+namespace cc {
+
+class CC_EXPORT TilingSetEvictionQueue {
+ public:
+  TilingSetEvictionQueue(PictureLayerTilingSet* tiling_set,
+                         TreePriority tree_priority);
+  ~TilingSetEvictionQueue();
+
+  Tile* Top();
+  const Tile* Top() const;
+  void Pop();
+  bool IsEmpty() const;
+
+ private:
+  bool AdvanceToNextCategory();
+  bool AdvanceToNextTilingRangeType();
+  bool AdvanceToNextValidTiling();
+
+  PictureLayerTilingSet::TilingRange CurrentTilingRange() const;
+  size_t CurrentTilingIndex() const;
+
+  Tile* PopEvictionTile();
+
+  PictureLayerTilingSet* tiling_set_;
+  TreePriority tree_priority_;
+
+  PictureLayerTiling::EvictionCategory current_category_;
+  size_t current_tiling_index_;
+  PictureLayerTilingSet::TilingRangeType current_tiling_range_type_;
+
+  const std::vector<Tile*>* current_eviction_tiles_;

[vmpstr, 2014/11/25 17:37:05]

Is it worth to make a struct here something like

struct EvictionData {
  const std::vector<Tile*>* tiles_;
  size_t index_;
  Tile* tile_;
} current_data_;

tile_ might even be:

Tile* tile() {
  if (tiles_ && index_ < tiles_->size())
    return (*tiles_)[index_];
  return nullptr;
}

(assuming that we point to the same tile as current)

Or maybe we should just rename the variables not to have current_* in front of
everything and leave a few comments to describe at a general level how this
queue will advance.

[USE eero AT chromium.org, 2014/11/26 14:20:46]

I took this route.

+  size_t current_eviction_tiles_index_;
+  Tile* current_tile_;
+};
+
+}  // namespace cc
+
+#endif  // CC_RESOURCES_TILING_SET_RASTER_QUEUE_H_