Splitting of layers for correct intersections

cc/trees/layer_tree_host_common.cc

Index: cc/trees/layer_tree_host_common.cc
diff --git a/cc/trees/layer_tree_host_common.cc b/cc/trees/layer_tree_host_common.cc
index 8d25539725914ee4d495f5ac580b86ae70aec0d4..ef468f9e85c418ae9329915ec3232fddc41a8f94 100644
--- a/cc/trees/layer_tree_host_common.cc
+++ b/cc/trees/layer_tree_host_common.cc
@@ -14,7 +14,6 @@
 #include "cc/layers/layer_iterator.h"
 #include "cc/layers/render_surface.h"
 #include "cc/layers/render_surface_impl.h"
-#include "cc/trees/layer_sorter.h"
 #include "cc/trees/layer_tree_impl.h"
 #include "ui/gfx/rect_conversions.h"
 #include "ui/gfx/transform.h"
@@ -25,20 +24,6 @@ ScrollAndScaleSet::ScrollAndScaleSet() {}
 
 ScrollAndScaleSet::~ScrollAndScaleSet() {}
 
-static void SortLayers(LayerList::iterator forst,
-                       LayerList::iterator end,
-                       void* layer_sorter) {
-  NOTREACHED();
-}
-
-static void SortLayers(LayerImplList::iterator first,
-                       LayerImplList::iterator end,
-                       LayerSorter* layer_sorter) {
-  DCHECK(layer_sorter);
-  TRACE_EVENT0("cc", "LayerTreeHostCommon::SortLayers");
-  layer_sorter->Sort(first, end);
-}
-
 template <typename LayerType>
 static gfx::Vector2dF GetEffectiveScrollDelta(LayerType* layer) {
   gfx::Vector2dF scroll_delta = layer->ScrollDelta();
@@ -1260,7 +1245,6 @@ static void RoundTranslationComponents(gfx::Transform* transform) {
 
 template <typename LayerType>
 struct SubtreeGlobals {
-  LayerSorter* layer_sorter;
   int max_texture_size;
   float device_scale_factor;
   float page_scale_factor;
@@ -2312,17 +2296,6 @@ static void CalculateDrawPropertiesInternal(
     return;
   }
 
-  // If preserves-3d then sort all the descendants in 3D so that they can be
-  // drawn from back to front. If the preserves-3d property is also set on the
-  // parent then skip the sorting as the parent will sort all the descendants
-  // anyway.
-  if (globals.layer_sorter && descendants.size() && layer->Is3dSorted() &&
-      !LayerIsInExisting3DRenderingContext(layer)) {
-    SortLayers(descendants.begin() + sorting_start_index,
-               descendants.end(),
-               globals.layer_sorter);
-  }
-
   UpdateAccumulatedSurfaceState<LayerType>(
       layer, local_drawable_content_rect_of_subtree, accumulated_surface_state);
 
@@ -2360,7 +2333,6 @@ static void ProcessCalcDrawPropsInputs(
   scaled_device_transform.Scale(inputs.device_scale_factor,
                                 inputs.device_scale_factor);
 
-  globals->layer_sorter = NULL;
   globals->max_texture_size = inputs.max_texture_size;
   globals->device_scale_factor =
       inputs.device_scale_factor * device_transform_scale;
@@ -2419,9 +2391,6 @@ void LayerTreeHostCommon::CalculateDrawProperties(
   DataForRecursion<LayerImpl> data_for_recursion;
   ProcessCalcDrawPropsInputs(*inputs, &globals, &data_for_recursion);
 
-  LayerSorter layer_sorter;
-  globals.layer_sorter = &layer_sorter;
-
   PreCalculateMetaInformationRecursiveData recursive_data;
   PreCalculateMetaInformation(inputs->root_layer, &recursive_data);
   std::vector<AccumulatedSurfaceState<LayerImpl> >