cc : Move screen space scale factor to root transform node

cc/trees/property_tree.h

Index: cc/trees/property_tree.h
diff --git a/cc/trees/property_tree.h b/cc/trees/property_tree.h
index 10896439072f987cfb54ea841abca1122b156359..f46f90cb4884860b3485fa1aee9c291bdd810197 100644
--- a/cc/trees/property_tree.h
+++ b/cc/trees/property_tree.h
@@ -221,9 +221,11 @@ class CC_EXPORT TransformTree final : public PropertyTree<TransformNode> {
   }
   float device_scale_factor() const { return device_scale_factor_; }
 
-  void SetDeviceTransform(const gfx::Transform& transform,
-                          gfx::PointF root_position);
-  void SetDeviceTransformScaleFactor(const gfx::Transform& transform);
+  void SetRootTransformsAndScales(float device_scale_factor,
+                                  float page_scale_factor_for_root,
+                                  const gfx::Transform& device_transform,
+                                  gfx::PointF root_position);
+
   float device_transform_scale_factor() const {
     return device_transform_scale_factor_;
   }
@@ -310,6 +312,10 @@ class CC_EXPORT TransformTree final : public PropertyTree<TransformNode> {
       TransformNode* node,
       TransformNode* parent_node);
   bool NeedsSourceToParentUpdate(TransformNode* node);
+  void SetContentsRootPostLocalTransform(const gfx::Transform& transform,
+                                         gfx::PointF root_position);
+  void SetScreenSpaceScaleOnRootNode(
+      gfx::Vector2dF screen_space_scale_components);
 
   bool source_to_parent_updates_allowed_;
   // When to_screen transform has perspective, the transform node's sublayer