Update from https://crrev.com/320931

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 <vector>
 
 #include "base/basictypes.h"
@@ skipping 29 matching lines @@
   // we'll just use the baked to_parent). These values will be ultimately stored
   // directly on the transform/scroll display list items when that's possible,
   // or potentially in a scroll tree.
   //
   // TODO(vollick): will be moved when accelerated effects are implemented.
   gfx::Transform pre_local;
   gfx::Transform local;
   gfx::Transform post_local;
 
   gfx::Transform to_parent;
-  gfx::Transform from_parent;
 
   gfx::Transform to_target;
   gfx::Transform from_target;
 
   gfx::Transform to_screen;
   gfx::Transform from_screen;
 
   int target_id;
   // This id is used for all content that draws into a render surface associated
   // with this transform node.
   int content_target_id;
 
   // TODO(vollick): will be moved when accelerated effects are implemented.
   bool needs_local_transform_update;
 
   bool is_invertible;
   bool ancestors_are_invertible;
 
   bool is_animated;
   bool to_screen_is_animated;
 
-  // We don't necessarily create a transform node to apply flattening. If we've
-  // skipped flattening for an ancestor, we must flatten the transform we
-  // inherit, but we don't necessarily need to flatten our local transform. We
-  // must therefore use two values to describe the flattening required for the
-  // local and inherited transforms.
+  // Flattening, when needed, is only applied to a node's inherited transform,
+  // never to its local transform.
   bool flattens_inherited_transform;
-  bool flattens_local_transform;
+
+  // This is true if the to_parent transform at every node on the path to the
+  // root is flat.
+  bool node_and_ancestors_are_flat;
+
   bool scrolls;
 
   bool needs_sublayer_scale;
   // This is used as a fallback when we either cannot adjust raster scale or if
   // the raster scale cannot be extracted from the screen space transform.
   float layer_scale_factor;
   gfx::Vector2dF sublayer_scale;
 
   // TODO(vollick): will be moved when accelerated effects are implemented.
   gfx::Vector2dF scroll_offset;
 
   void set_to_parent(const gfx::Transform& transform) {
     to_parent = transform;
-    is_invertible = to_parent.GetInverse(&from_parent);
+    is_invertible = to_parent.IsInvertible();
   }
 };
 
 typedef TreeNode<TransformNodeData> TransformNode;
 
 struct CC_EXPORT ClipNodeData {
   ClipNodeData();
 
   gfx::RectF clip;
   gfx::RectF combined_clip;
@@ skipping 85 matching lines @@
   void UpdateSnapping(TransformNode* node);
 };
 
 class CC_EXPORT ClipTree final : public PropertyTree<ClipNode> {};
 
 class CC_EXPORT OpacityTree final : public PropertyTree<OpacityNode> {};
 
 }  // namespace cc
 
 #endif  // CC_TREES_PROPERTY_TREE_H_