cc: Start using raster/eviction iterators.

cc/resources/tile_priority_queue.cc

Index: cc/resources/tile_priority_queue.cc
diff --git a/cc/resources/tile_priority_queue.cc b/cc/resources/tile_priority_queue.cc
new file mode 100644
index 0000000000000000000000000000000000000000..90c0cb1492a662a6982077ff5c9a838cd1543880
--- /dev/null
+++ b/cc/resources/tile_priority_queue.cc
@@ -0,0 +1,64 @@
+// 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/resources/tile_priority_queue.h"
+
+#include <vector>
+
+#include "cc/layers/picture_layer_impl.h"
+
+namespace cc {
+
+TilePriorityQueue::PairedPictureLayer::PairedPictureLayer()
+    : active_layer(NULL), pending_layer(NULL) {
+}
+
+TilePriorityQueue::PairedPictureLayer::~PairedPictureLayer() {
+}
+
+TilePriorityQueue::~TilePriorityQueue() {
+}
+
+void TilePriorityQueue::GetPairedPictureLayers(
+    const std::vector<PictureLayerImpl*>& layers,
+    std::vector<PairedPictureLayer>* paired_layers) const {
+  DCHECK(paired_layers);
+  DCHECK(paired_layers->empty());
+
+  for (std::vector<PictureLayerImpl*>::const_iterator it = layers.begin();
+       it != layers.end();
+       ++it) {
+    PictureLayerImpl* layer = *it;
+
+    // TODO(vmpstr): Iterators and should handle this instead. crbug.com/381704
+    if (!layer->HasValidTilePriorities())
+      continue;
+
+    PictureLayerImpl* twin_layer = layer->GetTwinLayer();
+
+    // Ignore the twin layer when tile priorities are invalid.
+    // TODO(vmpstr): Iterators should handle this instead. crbug.com/381704
+    if (twin_layer && !twin_layer->HasValidTilePriorities())
+      twin_layer = NULL;
+
+    PairedPictureLayer paired_layer;
+    WhichTree tree = layer->GetTree();
+
+    // If the current tree is ACTIVE_TREE, then always generate a paired_layer.
+    // If current tree is PENDING_TREE, then only generate a paired_layer if
+    // there is no twin layer.
+    if (tree == ACTIVE_TREE) {
+      DCHECK(!twin_layer || twin_layer->GetTree() == PENDING_TREE);
+      paired_layer.active_layer = layer;
+      paired_layer.pending_layer = twin_layer;
+      paired_layers->push_back(paired_layer);
+    } else if (!twin_layer) {
+      paired_layer.active_layer = NULL;
+      paired_layer.pending_layer = layer;
+      paired_layers->push_back(paired_layer);
+    }
+  }
+}
+
+}  // namespace cc