cc : Use dynamically calculated target space transforms

cc/trees/draw_property_utils.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/draw_property_utils.h"
 
 #include <stddef.h>
 
 #include <vector>
 
@@ skipping 785 matching lines @@
     // must combine clips. For each clip node, we save the clip rects in its
     // target space. So, we need to get the ancestor clip rect in the current
     // clip node's target space.
     gfx::RectF parent_combined_clip_in_target_space =
         parent_clip_node->combined_clip_in_target_space;
     gfx::RectF parent_clip_in_target_space =
         parent_clip_node->clip_in_target_space;
     if (parent_target_transform_node &&
         parent_target_transform_node->id != clip_node->target_transform_id &&
         non_root_surfaces_enabled) {
-      success &= property_trees->ComputeTransformToTarget(
-          parent_target_transform_node->id, clip_node->target_effect_id,
+      success &= property_trees->ComputeTransformFromTarget(
+          clip_node->target_transform_id, parent_clip_node->target_effect_id,

[jaydasika, 2016/07/28 22:55:56]

I am changing it to force it to take the dynamically calculated value
path(otherwise they are equivalent). This is the inverse of surface draw
transform, so I think it makes more sense to compute from target.(which is most
likely already in the cache as we would have calculated in in
SetSurfaceDrawTransform).

           &parent_to_current);
       // We don't have to apply surface contents scale when target is root.
       if (clip_node->target_effect_id != EffectTree::kContentsRootNodeId) {
         const EffectNode* target_effect_node =
             effect_tree.Node(clip_node->target_effect_id);
         PostConcatSurfaceContentsScale(target_effect_node, &parent_to_current);
 #if DCHECK_IS_ON()
         VerifySurfaceContentsScalesMatch(clip_node->target_effect_id,
                                          clip_node->target_transform_id,
                                          effect_tree, transform_tree);
@@ skipping 786 matching lines @@
 void UpdateElasticOverscroll(PropertyTrees* property_trees,
                              const Layer* overscroll_elasticity_layer,
                              const gfx::Vector2dF& elastic_overscroll) {
   UpdateElasticOverscrollInternal(property_trees, overscroll_elasticity_layer,
                                   elastic_overscroll);
 }
 
 }  // namespace draw_property_utils
 
 }  // namespace cc