cc: Change TileManager iterators to be queues.

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 a2c8111e0e7329d569bb383dafb1b65c3b6cdfea..322cc15c74ea98921891b3dbd2529b04a9ae5c9a 100644
--- a/cc/trees/layer_tree_host_impl.cc
+++ b/cc/trees/layer_tree_host_impl.cc
@@ -45,6 +45,7 @@
 #include "cc/quads/shared_quad_state.h"
 #include "cc/quads/solid_color_draw_quad.h"
 #include "cc/quads/texture_draw_quad.h"
+#include "cc/resources/eviction_tile_priority_queue.h"
 #include "cc/resources/gpu_raster_worker_pool.h"
 #include "cc/resources/image_copy_raster_worker_pool.h"
 #include "cc/resources/image_raster_worker_pool.h"
@@ -52,6 +53,7 @@
 #include "cc/resources/picture_layer_tiling.h"
 #include "cc/resources/pixel_buffer_raster_worker_pool.h"
 #include "cc/resources/prioritized_resource_manager.h"
+#include "cc/resources/raster_tile_priority_queue.h"
 #include "cc/resources/raster_worker_pool.h"
 #include "cc/resources/resource_pool.h"
 #include "cc/resources/texture_mailbox_deleter.h"
@@ -1246,7 +1248,64 @@ void LayerTreeHostImpl::DidInitializeVisibleTile() {
     client_->DidInitializeVisibleTileOnImplThread();
 }
 
-const std::vector<PictureLayerImpl*>& LayerTreeHostImpl::GetPictureLayers() {
+void LayerTreeHostImpl::GetPictureLayerImplPairs(
+    std::vector<PictureLayerImpl::Pair>* layer_pairs) const {
+  layer_pairs->clear();

[reveman, 2014/07/19 00:45:50]

Let's make this the responsibility of the caller instead.
DCHECK(layer_pairs->is_empty())

[vmpstr, 2014/07/20 01:15:04]

Done.

+  // Reserve a maximum possible paired layers.
+  layer_pairs->reserve(picture_layers_.size());

[reveman, 2014/07/19 00:45:50]

Please have the caller reuse the same vector instead of using reserve() here.

[vmpstr, 2014/07/20 01:15:04]

Done.

+
+  for (std::vector<PictureLayerImpl*>::const_iterator it =
+           picture_layers_.begin();
+       it != picture_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;
+
+    PictureLayerImpl::Pair layer_pair;

[reveman, 2014/07/19 00:45:50]

This temporary variable seem unnecessary. How about with a ctor that takes 2
layers as input we do .push_back(PictureLayerImpl::Pair(layer, twin_layer))
below instead?

[vmpstr, 2014/07/20 01:15:04]

Done.

+    WhichTree tree = layer->GetTree();

[reveman, 2014/07/19 00:45:50]

this temporary variable seem unnecessary too

[vmpstr, 2014/07/20 01:15:04]

Done.

+
+    // If the current tree is ACTIVE_TREE, then always generate a layer_pair.
+    // If current tree is PENDING_TREE, then only generate a layer_pair if
+    // there is no twin layer.
+    if (tree == ACTIVE_TREE) {
+      DCHECK(!twin_layer || twin_layer->GetTree() == PENDING_TREE);
+      layer_pair.active = layer;
+      layer_pair.pending = twin_layer;
+      layer_pairs->push_back(layer_pair);
+    } else if (!twin_layer) {
+      layer_pair.active = NULL;
+      layer_pair.pending = layer;
+      layer_pairs->push_back(layer_pair);
+    }
+  }
+}
+
+void LayerTreeHostImpl::BuildRasterQueue(RasterTilePriorityQueue* queue,
+                                         TreePriority tree_priority) {
+  std::vector<PictureLayerImpl::Pair> layer_pairs;
+  GetPictureLayerImplPairs(&layer_pairs);
+  queue->Build(layer_pairs, tree_priority);
+}
+
+void LayerTreeHostImpl::BuildEvictionQueue(EvictionTilePriorityQueue* queue,
+                                           TreePriority tree_priority) {
+  std::vector<PictureLayerImpl::Pair> layer_pairs;
+  GetPictureLayerImplPairs(&layer_pairs);
+  queue->Build(layer_pairs, tree_priority);
+}
+
+const std::vector<PictureLayerImpl*>& LayerTreeHostImpl::GetPictureLayers()
+    const {
   return picture_layers_;
 }