Update from https://crrev.com/320343

cc/trees/layer_tree_host_common.cc

 // 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/trees/layer_tree_host_common.h"
 
 #include <algorithm>
 
 #include "base/trace_event/trace_event.h"
 #include "cc/base/math_util.h"
 #include "cc/layers/heads_up_display_layer_impl.h"
 #include "cc/layers/layer.h"
 #include "cc/layers/layer_impl.h"
 #include "cc/layers/layer_iterator.h"
 #include "cc/layers/render_surface.h"
 #include "cc/layers/render_surface_impl.h"
 #include "cc/trees/draw_property_utils.h"
-#include "cc/trees/layer_sorter.h"
 #include "cc/trees/layer_tree_host.h"
 #include "cc/trees/layer_tree_impl.h"
 #include "ui/gfx/geometry/rect_conversions.h"
 #include "ui/gfx/geometry/vector2d_conversions.h"
 #include "ui/gfx/transform.h"
 #include "ui/gfx/transform_util.h"
 
 namespace cc {
 
 ScrollAndScaleSet::ScrollAndScaleSet()
     : page_scale_delta(1.f), top_controls_delta(0.f) {
 }
 
 ScrollAndScaleSet::~ScrollAndScaleSet() {}
 
-static void SortLayers(LayerList::iterator first,
-                       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) {
   // Layer's scroll offset can have an integer part and fractional part.
   // Due to Blink's limitation, it only counter-scrolls the position-fixed
   // layer using the integer part of Layer's scroll offset.
   // CC scrolls the layer using the full scroll offset, so we have to
   // add the ScrollCompensationAdjustment (fractional part of the scroll
   // offset) to the effective scroll delta which is used to counter-scroll
   // the position-fixed layer.
   gfx::Vector2dF scroll_delta =
@@ skipping 1063 matching lines @@
       layer_maximum_animated_scale *
       std::max(ancestor_transform_scales.x(), ancestor_transform_scales.y());
 }
 
 template <typename LayerTypePtr>
 static inline void MarkLayerWithRenderSurfaceLayerListId(
     LayerTypePtr layer,
     int current_render_surface_layer_list_id) {
   layer->draw_properties().last_drawn_render_surface_layer_list_id =
       current_render_surface_layer_list_id;
+  layer->draw_properties().layer_or_descendant_is_drawn =
+      !!current_render_surface_layer_list_id;
 }
 
 template <typename LayerTypePtr>
 static inline void MarkMasksWithRenderSurfaceLayerListId(
     LayerTypePtr layer,
     int current_render_surface_layer_list_id) {
   if (layer->mask_layer()) {
     MarkLayerWithRenderSurfaceLayerListId(layer->mask_layer(),
                                           current_render_surface_layer_list_id);
   }
@@ skipping 52 matching lines @@
   PreCalculateMetaInformationRecursiveData()
       : layer_or_descendant_has_copy_request(false),
         layer_or_descendant_has_input_handler(false),
         num_unclipped_descendants(0) {}
 
   void Merge(const PreCalculateMetaInformationRecursiveData& data) {
     layer_or_descendant_has_copy_request |=
         data.layer_or_descendant_has_copy_request;
     layer_or_descendant_has_input_handler |=
         data.layer_or_descendant_has_input_handler;
-    num_unclipped_descendants +=
-        data.num_unclipped_descendants;
+    num_unclipped_descendants += data.num_unclipped_descendants;
   }
 };
 
 static void ValidateRenderSurface(LayerImpl* layer) {
   // This test verifies that there are no cases where a LayerImpl needs
   // a render surface, but doesn't have one.
   if (layer->render_surface())
     return;
 
   DCHECK(layer->filters().IsEmpty()) << "layer: " << layer->id();
@@ skipping 11 matching lines @@
 // Recursively walks the layer tree to compute any information that is needed
 // before doing the main recursion.
 template <typename LayerType>
 static void PreCalculateMetaInformation(
     LayerType* layer,
     PreCalculateMetaInformationRecursiveData* recursive_data) {
   ValidateRenderSurface(layer);
 
   layer->draw_properties().sorted_for_recursion = false;
   layer->draw_properties().has_child_with_a_scroll_parent = false;
+  layer->draw_properties().layer_or_descendant_is_drawn = false;
   layer->draw_properties().visited = false;
 
   if (!HasInvertibleOrAnimatedTransform(layer)) {
     // Layers with singular transforms should not be drawn, the whole subtree
     // can be skipped.
     return;
   }
 
   if (layer->clip_parent())
     recursive_data->num_unclipped_descendants++;
@@ skipping 26 matching lines @@
   layer->draw_properties().num_unclipped_descendants =
       recursive_data->num_unclipped_descendants;
   layer->draw_properties().layer_or_descendant_has_copy_request =
       recursive_data->layer_or_descendant_has_copy_request;
   layer->draw_properties().layer_or_descendant_has_input_handler =
       recursive_data->layer_or_descendant_has_input_handler;
 }
 
 template <typename LayerType>
 struct SubtreeGlobals {
-  LayerSorter* layer_sorter;
   int max_texture_size;
   float device_scale_factor;
   float page_scale_factor;
   const LayerType* page_scale_application_layer;
   gfx::Vector2dF elastic_overscroll;
   const LayerType* elastic_overscroll_application_layer;
   bool can_adjust_raster_scales;
   bool can_render_to_separate_surface;
   bool layers_always_allowed_lcd_text;
 };
@@ skipping 514 matching lines @@
   layer_draw_properties.target_space_transform = combined_transform;
   // M[draw] = M[parent] * LT * S[layer2content]
   layer_draw_properties.target_space_transform.Scale(
       SK_MScalar1 / layer->contents_scale_x(),
       SK_MScalar1 / layer->contents_scale_y());
 
   // The layer's screen_space_transform represents the transform between root
   // layer's "screen space" and local content space.
   layer_draw_properties.screen_space_transform =
       data_from_ancestor.full_hierarchy_matrix;
-  if (layer->should_flatten_transform())
-    layer_draw_properties.screen_space_transform.FlattenTo2d();
   layer_draw_properties.screen_space_transform.PreconcatTransform
       (layer_draw_properties.target_space_transform);
 
   // Adjusting text AA method during animation may cause repaints, which in-turn
   // causes jank.
   bool adjust_text_aa =
       !animating_opacity_to_screen && !animating_transform_to_screen;
   bool layer_can_use_lcd_text = true;
   bool subtree_can_use_lcd_text = true;
   if (!globals.layers_always_allowed_lcd_text) {
@@ skipping 98 matching lines @@
     layer_draw_properties.target_space_transform_is_animating =
         animating_transform_to_target;
     layer_draw_properties.screen_space_transform_is_animating =
         animating_transform_to_screen;
 
     // Update the aggregate hierarchy matrix to include the transform of the
     // newly created RenderSurfaceImpl.
     data_for_children.full_hierarchy_matrix.PreconcatTransform(
         render_surface->draw_transform());
 
+    // A render surface inherently acts as a flattening point for the content of
+    // its descendants.
+    data_for_children.full_hierarchy_matrix.FlattenTo2d();
+
     if (layer->mask_layer()) {
       DrawProperties<LayerType>& mask_layer_draw_properties =
           layer->mask_layer()->draw_properties();
       mask_layer_draw_properties.render_target = layer;
       mask_layer_draw_properties.visible_content_rect =
           gfx::Rect(layer->content_bounds());
     }
 
     if (layer->replica_layer() && layer->replica_layer()->mask_layer()) {
       DrawProperties<LayerType>& replica_mask_draw_properties =
@@ skipping 258 matching lines @@
       descendants.push_back(child);
     }
 
     child->draw_properties().num_descendants_added =
         descendants.size() -
         child->draw_properties().index_of_first_descendants_addition;
     child->draw_properties().num_render_surfaces_added =
         render_surface_layer_list->size() -
         child->draw_properties()
             .index_of_first_render_surface_layer_list_addition;
+    layer_draw_properties.layer_or_descendant_is_drawn |=
+        child->draw_properties().layer_or_descendant_is_drawn;
   }
 
   // Add the unsorted layer list contributions, if necessary.
   if (child_order_changed) {
     SortLayerListContributions(
         *layer,
         GetLayerListForSorting(render_surface_layer_list),
         render_surface_layer_list_child_sorting_start_index,
         &GetNewRenderSurfacesStartIndexAndCount<LayerType>);
 
@@ skipping 133 matching lines @@
   }
 
   SavePaintPropertiesLayer(layer);
 
   // If neither this layer nor any of its children were added, early out.
   if (sorting_start_index == descendants.size()) {
     DCHECK(!render_to_separate_surface || IsRootLayer(layer));
     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);
 
   if (layer->HasContributingDelegatedRenderPasses()) {
     layer->render_target()->render_surface()->
         AddContributingDelegatedRenderPassLayer(layer);
   }
 }  // NOLINT(readability/fn_size)
 
 template <typename LayerType, typename RenderSurfaceLayerListType>
@@ skipping 17 matching lines @@
       MathUtil::ComputeTransform2dScaleComponents(inputs.device_transform, 1.f);
   // Not handling the rare case of different x and y device scale.
   float device_transform_scale =
       std::max(device_transform_scale_components.x(),
                device_transform_scale_components.y());
 
   gfx::Transform scaled_device_transform = inputs.device_transform;
   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;
   globals->page_scale_factor = inputs.page_scale_factor;
   globals->page_scale_application_layer = inputs.page_scale_application_layer;
   globals->elastic_overscroll = inputs.elastic_overscroll;
   globals->elastic_overscroll_application_layer =
       inputs.elastic_overscroll_application_layer;
   globals->can_render_to_separate_surface =
       inputs.can_render_to_separate_surface;
@@ skipping 143 matching lines @@
   DCHECK(inputs->root_layer->render_surface());
 }
 
 void LayerTreeHostCommon::CalculateDrawProperties(
     CalcDrawPropsImplInputs* inputs) {
   LayerImplList dummy_layer_list;
   SubtreeGlobals<LayerImpl> globals;
   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>> accumulated_surface_state;
   CalculateDrawPropertiesInternal<LayerImpl>(
       inputs->root_layer,
       globals,
       data_for_recursion,
       inputs->render_surface_layer_list,
       &dummy_layer_list,
       &accumulated_surface_state,
       inputs->current_render_surface_layer_list_id);
 
   // The dummy layer list should not have been used.
   DCHECK_EQ(0u, dummy_layer_list.size());
   // A root layer render_surface should always exist after
   // CalculateDrawProperties.
   DCHECK(inputs->root_layer->render_surface());
 }
 
 }  // namespace cc