cc: Start using raster/eviction iterators.

cc/trees/layer_tree_host_impl.cc

Index: cc/trees/layer_tree_host_impl.cc
diff --git a/cc/trees/layer_tree_host_impl.cc b/cc/trees/layer_tree_host_impl.cc
index 8050377440ffb539d1b56570176a9c2e6dcad118..bbdd0241a25a0519de268db2e17384c0754ddc4b 100644
--- a/cc/trees/layer_tree_host_impl.cc
+++ b/cc/trees/layer_tree_host_impl.cc
@@ -1244,7 +1244,8 @@ void LayerTreeHostImpl::DidInitializeVisibleTile() {
     client_->DidInitializeVisibleTileOnImplThread();
 }
 
-const std::vector<PictureLayerImpl*>& LayerTreeHostImpl::GetPictureLayers() {
+const std::vector<PictureLayerImpl*>& LayerTreeHostImpl::GetPictureLayers()
+    const {
   return picture_layers_;
 }
 
@@ -1270,6 +1271,26 @@ void LayerTreeHostImpl::NotifyTileStateChanged(const Tile* tile) {
   }
 }
 
+TilePriorityQueue* LayerTreeHostImpl::RebuildRasterQueue(
+    TreePriority tree_priority) {
+  // TODO(vmpstr): Investigate if we can skip preparation if nothing changed
+  // (priorities, etc)
+  std::vector<PairedPictureLayer> paired_layers;
+  GetPairedPictureLayers(&paired_layers);
+  raster_queue_.Prepare(paired_layers, tree_priority);
+  return &raster_queue_;
+}
+
+TilePriorityQueue* LayerTreeHostImpl::RebuildEvictionQueue(
+    TreePriority tree_priority) {
+  // TODO(vmpstr): Investigate if we can skip preparation if nothing changed
+  // (priorities, etc)
+  std::vector<PairedPictureLayer> paired_layers;
+  GetPairedPictureLayers(&paired_layers);
+  eviction_queue_.Prepare(paired_layers, tree_priority);
+  return &eviction_queue_;
+}
+
 void LayerTreeHostImpl::SetMemoryPolicy(const ManagedMemoryPolicy& policy) {
   SetManagedMemoryPolicy(policy, zero_budget_);
 }
@@ -1997,6 +2018,49 @@ void LayerTreeHostImpl::EnforceZeroBudget(bool zero_budget) {
   SetManagedMemoryPolicy(cached_managed_memory_policy_, zero_budget);
 }
 
+void LayerTreeHostImpl::GetPairedPictureLayers(
+    std::vector<PairedPictureLayer>* paired_layers) const {
+  const std::vector<PictureLayerImpl*>& layers = GetPictureLayers();
+
+  paired_layers->clear();
+  // Reserve a maximum possible paired layers.
+  paired_layers->reserve(layers.size());
+
+  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);
+    }
+  }
+}
+
 bool LayerTreeHostImpl::InitializeRenderer(
     scoped_ptr<OutputSurface> output_surface) {
   TRACE_EVENT0("cc", "LayerTreeHostImpl::InitializeRenderer");