Remove owning_id from EffectNode and replace it by an opaque stable_id

cc/trees/effect_node.h

 // Copyright 2016 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_EFFECT_NODE_H_
 #define CC_TREES_EFFECT_NODE_H_
 
 #include "cc/base/filter_operations.h"
 #include "cc/cc_export.h"
 #include "third_party/skia/include/core/SkBlendMode.h"
 #include "ui/gfx/geometry/point_f.h"
 #include "ui/gfx/geometry/size_f.h"
 
 namespace base {
 namespace trace_event {
 class TracedValue;
 }  // namespace trace_event
 }  // namespace base
 
 namespace cc {
 
 struct CC_EXPORT EffectNode {
   EffectNode();
   EffectNode(const EffectNode& other);
 
   // The node index of this node in the effect tree node vector.
   int id;
   // The node index of the parent node in the effect tree node vector.
   int parent_id;
-  // The layer id of the layer that owns this node.
-  int owning_layer_id;
+
+  // An identifer for this effect that is generally stable across commits.
+  int stable_id;
 
   float opacity;
   float screen_space_opacity;
 
   FilterOperations filters;
   FilterOperations background_filters;
   gfx::PointF filters_origin;
 
   SkBlendMode blend_mode;
 
@@ skipping 12 matching lines @@
   bool has_potential_filter_animation;
   bool has_potential_opacity_animation;
   bool is_currently_animating_filter;
   bool is_currently_animating_opacity;
   // We need to track changes to effects on the compositor to compute damage
   // rect.
   bool effect_changed;
   bool subtree_has_copy_request;
   int transform_id;
   int clip_id;
-  // Effect node id of which this effect contributes to.
+
+  // This is the id of the ancestor effect node that induces a
+  // RenderSurfaceImpl.
   int target_id;
   int mask_layer_id;
   int closest_ancestor_with_copy_request_id;
 
   bool operator==(const EffectNode& other) const;
 
   void AsValueInto(base::trace_event::TracedValue* value) const;
 };
 
 }  // namespace cc
 
 #endif  // CC_TREES_EFFECT_NODE_H_