Revert of Splitting of layers for correct intersections

cc/trees/layer_tree_host_common_perftest.cc

Index: cc/trees/layer_tree_host_common_perftest.cc
diff --git a/cc/trees/layer_tree_host_common_perftest.cc b/cc/trees/layer_tree_host_common_perftest.cc
index 1732e5588981f89d175935ae9d984b6cd5c05ad1..73d5c1d0d413db93dddcdee3f1194d5167967ac4 100644
--- a/cc/trees/layer_tree_host_common_perftest.cc
+++ b/cc/trees/layer_tree_host_common_perftest.cc
@@ -25,6 +25,7 @@
 #include "cc/test/layer_tree_json_parser.h"
 #include "cc/test/layer_tree_test.h"
 #include "cc/test/paths.h"
+#include "cc/trees/layer_sorter.h"
 #include "cc/trees/layer_tree_impl.h"
 #include "testing/perf/perf_test.h"
 
@@ -161,7 +162,55 @@
   }
 };
 
-class BspTreePerfTest : public CalcDrawPropsImplTest {
+class LayerSorterMainTest : public CalcDrawPropsImplTest {
+ public:
+  void RunSortLayers() { RunTest(false, false, false); }
+
+  void BeginTest() override { PostSetNeedsCommitToMainThread(); }
+
+  void DrawLayersOnThread(LayerTreeHostImpl* host_impl) override {
+    LayerTreeImpl* active_tree = host_impl->active_tree();
+    // First build the tree and then we'll start running tests on layersorter
+    // itself
+    bool can_render_to_separate_surface = true;
+    int max_texture_size = 8096;
+    DoCalcDrawPropertiesImpl(can_render_to_separate_surface,
+                             max_texture_size,
+                             active_tree,
+                             host_impl);
+
+    // Behaviour of this test is different from that of sorting in practice.
+    // In this case, all layers that exist in any 3D context are put into a list
+    // and are sorted as one big 3D context instead of several smaller ones.
+    BuildLayerImplList(active_tree->root_layer(), &base_list_);
+    timer_.Reset();
+    do {
+      // Here we'll move the layers into a LayerImpl list of their own to be
+      // sorted so we don't have a sorted list for every run after the first
+      LayerImplList test_list = base_list_;
+      layer_sorter_.Sort(test_list.begin(), test_list.end());
+      timer_.NextLap();
+    } while (!timer_.HasTimeLimitExpired());
+
+    EndTest();
+  }
+
+  void BuildLayerImplList(LayerImpl* layer, LayerImplList* list) {
+    if (layer->Is3dSorted()) {
+      list->push_back(layer);
+    }
+
+    for (size_t i = 0; i < layer->children().size(); i++) {
+      BuildLayerImplList(layer->children()[i], list);
+    }
+  }
+
+ private:
+  LayerImplList base_list_;
+  LayerSorter layer_sorter_;
+};
+
+class BspTreePerfTest : public LayerSorterMainTest {
  public:
   void RunSortLayers() { RunTest(false, false, false); }
 
@@ -212,18 +261,7 @@
     EndTest();
   }
 
-  void BuildLayerImplList(LayerImpl* layer, LayerImplList* list) {
-    if (layer->Is3dSorted()) {
-      list->push_back(layer);
-    }
-
-    for (size_t i = 0; i < layer->children().size(); i++) {
-      BuildLayerImplList(layer->children()[i], list);
-    }
-  }
-
  private:
-  LayerImplList base_list_;
   int num_duplicates_;
 };
 
@@ -275,13 +313,13 @@
   RunCalcDrawProps();
 }
 
-TEST_F(BspTreePerfTest, LayerSorterCubes) {
+TEST_F(LayerSorterMainTest, LayerSorterCubes) {
   SetTestName("layer_sort_cubes");
   ReadTestFile("layer_sort_cubes");
   RunSortLayers();
 }
 
-TEST_F(BspTreePerfTest, LayerSorterRubik) {
+TEST_F(LayerSorterMainTest, LayerSorterRubik) {
   SetTestName("layer_sort_rubik");
   ReadTestFile("layer_sort_rubik");
   // TODO(vollick): Remove verify_property_trees setting after