cc : Move screen space scale factor to root transform node

cc/trees/layer_tree_impl.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_impl.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <algorithm>
@@ skipping 1014 matching lines @@
         const RenderSurfaceImpl* occlusion_surface =
             occlusion_tracker.OcclusionSurfaceForContributingSurface();
         gfx::Transform draw_transform;
         if (occlusion_surface) {
           // We are calculating transform between two render surfaces. So, we
           // need to apply the surface contents scale at target and remove the
           // surface contents scale at source.
           property_trees()->ComputeTransformToTarget(
               it->render_surface()->TransformTreeIndex(),
               occlusion_surface->EffectTreeIndex(), &draw_transform);
-          // We don't have to apply surface contents scale when target is root.
-          if (occlusion_surface->EffectTreeIndex() !=
-              EffectTree::kContentsRootNodeId) {
-            const EffectNode* occlusion_effect_node =
-                property_trees()->effect_tree.Node(
-                    occlusion_surface->EffectTreeIndex());
-            draw_property_utils::PostConcatSurfaceContentsScale(
-                occlusion_effect_node, &draw_transform);
-          }
+          const EffectNode* occlusion_effect_node =
+              property_trees()->effect_tree.Node(
+                  occlusion_surface->EffectTreeIndex());
+          draw_property_utils::PostConcatSurfaceContentsScale(
+              occlusion_effect_node, &draw_transform);
           const EffectNode* effect_node = property_trees()->effect_tree.Node(
               it->render_surface()->EffectTreeIndex());
           draw_property_utils::ConcatInverseSurfaceContentsScale(
               effect_node, &draw_transform);
         }
 
         Occlusion occlusion =
             occlusion_tracker.GetCurrentOcclusionForContributingSurface(
                 draw_transform);
         it->render_surface()->set_occlusion_in_content_space(occlusion);
@@ skipping 1019 matching lines @@
 
 void LayerTreeImpl::ResetAllChangeTracking() {
   layers_that_should_push_properties_.clear();
   // Iterate over all layers, including masks.
   for (auto& layer : *layers_)
     layer->ResetChangeTracking();
   property_trees_.ResetAllChangeTracking();
 }
 
 }  // namespace cc