cc : Reland move screen space scale factor to root transform node

cc/trees/property_tree_builder.cc

 // Copyright 2014 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/property_tree_builder.h"
 
 #include <stddef.h>
 
 #include <map>
 #include <set>
@@ skipping 618 matching lines @@
       kInvalidPropertyTreeNodeId);
 
   node->has_potential_animation = has_potentially_animated_transform;
   node->is_currently_animating = TransformIsAnimating(layer);
   if (has_potentially_animated_transform) {
     node->has_only_translation_animations =
         HasOnlyTranslationTransforms(layer);
   }
 
   float post_local_scale_factor = 1.0f;
-  if (is_root)
-    post_local_scale_factor =
-        data_for_children->property_trees->transform_tree.device_scale_factor();
 
   if (is_page_scale_layer) {
-    post_local_scale_factor *= data_from_ancestor.page_scale_factor;
+    if (!is_root)
+      post_local_scale_factor *= data_from_ancestor.page_scale_factor;
     data_for_children->property_trees->transform_tree.set_page_scale_factor(
         data_from_ancestor.page_scale_factor);
   }
 
   node->source_node_id = source_index;
   node->post_local_scale_factor = post_local_scale_factor;
   if (is_root) {
-    data_for_children->property_trees->transform_tree.SetDeviceTransform(
-        *data_from_ancestor.device_transform, layer->position());
+    float page_scale_factor_for_root =
+        is_page_scale_layer ? data_from_ancestor.page_scale_factor : 1.f;
+    data_for_children->property_trees->transform_tree
+        .SetRootTransformsAndScales(data_for_children->property_trees
+                                        ->transform_tree.device_scale_factor(),
+                                    page_scale_factor_for_root,
+                                    *data_from_ancestor.device_transform,
+                                    layer->position());
     data_for_children->property_trees->transform_tree
         .SetDeviceTransformScaleFactor(*data_from_ancestor.device_transform);
   } else {
     node->source_offset = source_offset;
     node->update_post_local_transform(layer->position(),
                                       TransformOrigin(layer));
   }
 
   if (is_overscroll_elasticity_layer) {
     DCHECK(!is_scrollable);
@@ skipping 688 matching lines @@
     const gfx::Transform& device_transform,
     PropertyTrees* property_trees,
     SkColor color) {
   if (!property_trees->needs_rebuild) {
     draw_property_utils::UpdatePageScaleFactor(
         property_trees, page_scale_layer, page_scale_factor,
         device_scale_factor, device_transform);
     draw_property_utils::UpdateElasticOverscroll(
         property_trees, overscroll_elasticity_layer, elastic_overscroll);
     property_trees->clip_tree.SetViewportClip(gfx::RectF(viewport));
-    property_trees->transform_tree.SetDeviceTransform(device_transform,
-                                                      root_layer->position());
+    float page_scale_factor_for_root =
+        page_scale_layer == root_layer ? page_scale_factor : 1.f;
+    property_trees->transform_tree.SetRootTransformsAndScales(
+        device_scale_factor, page_scale_factor_for_root, device_transform,
+        root_layer->position());
     return;
   }
 
   property_trees->sequence_number++;
 
   DataForRecursion<LayerType> data_for_recursion;
   data_for_recursion.property_trees = property_trees;
   data_for_recursion.transform_tree_parent = nullptr;
   data_for_recursion.transform_fixed_parent = nullptr;
   data_for_recursion.render_target = kRootPropertyTreeNodeId;
@@ skipping 117 matching lines @@
     color = SkColorSetA(color, 255);
   BuildPropertyTreesTopLevelInternal(
       root_layer, page_scale_layer, inner_viewport_scroll_layer,
       outer_viewport_scroll_layer, overscroll_elasticity_layer,
       elastic_overscroll, page_scale_factor, device_scale_factor, viewport,
       device_transform, property_trees, color);
   property_trees->ResetCachedData();
 }
 
 }  // namespace cc