Document some transform node animation fields.

cc/trees/property_tree.h

 // 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.
 
 #ifndef CC_TREES_PROPERTY_TREE_H_
 #define CC_TREES_PROPERTY_TREE_H_
 
 #include <stddef.h>
 
 #include <memory>
@@ skipping 283 matching lines @@
 
   bool source_to_parent_updates_allowed_;
   // When to_screen transform has perspective, the transform node's sublayer
   // scale is calculated using page scale factor, device scale factor and the
   // scale factor of device transform. So we need to store them explicitly.
   float page_scale_factor_;
   float device_scale_factor_;
   float device_transform_scale_factor_;
   std::vector<int> nodes_affected_by_inner_viewport_bounds_delta_;
   std::vector<int> nodes_affected_by_outer_viewport_bounds_delta_;
+  // TODO(wkorman): Consider renaming cached_data_ to better describe what's

[chrishtr, 2017/05/13 01:07:18]

Not sure if this needs to be a TODO in the code.

[wkorman, 2017/05/15 19:48:27]

Done.

+  // cached.
   std::vector<TransformCachedNodeData> cached_data_;
   std::vector<StickyPositionNodeData> sticky_position_data_;
 };
 
 struct StickyPositionNodeData {
   int scroll_ancestor;
   LayerStickyPositionConstraint constraints;
 
   // This is the offset that blink has already applied to counteract the main
   // thread scroll offset of the scroll ancestor. We need to account for this
@@ skipping 410 matching lines @@
   DrawTransforms& GetDrawTransforms(int transform_id, int effect_id) const;
   DrawTransformData& FetchDrawTransformsDataFromCache(int transform_id,
                                                       int effect_id) const;
 
   PropertyTreesCachedData cached_data_;
 };
 
 }  // namespace cc
 
 #endif  // CC_TREES_PROPERTY_TREE_H_