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 6edac892bc4636e2022d51fb1fd4d79f137ae9bc..ce6b618fc528108dc2781cf4981937b672f0c20f 100644
--- a/cc/trees/property_tree.h
+++ b/cc/trees/property_tree.h
@@ -224,9 +224,11 @@ 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_;
   }
@@ -313,6 +315,10 @@ 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