Refactor PropertyTreeState as GeometryPropertyTreeState

third_party/WebKit/Source/platform/graphics/paint/PropertyTreeState.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 PropertyTreeState_h
-#define PropertyTreeState_h
-
-#include "platform/graphics/paint/ClipPaintPropertyNode.h"
-#include "platform/graphics/paint/EffectPaintPropertyNode.h"
-#include "platform/graphics/paint/TransformPaintPropertyNode.h"
-#include "wtf/HashFunctions.h"
-#include "wtf/HashTraits.h"
-
-namespace blink {
-
-// Represents the combination of transform, clip and effect nodes for a particular coordinate space.
-// See GeometryMapper.
-// Scroll nodes (ScrollPaintPropertyNode) are not needed for mapping geometry and have been left off
-// of this structure.
-// TODO(pdr): Rename this GeometryPropertyTreeState.
-struct PropertyTreeState {
-    PropertyTreeState() : PropertyTreeState(nullptr, nullptr, nullptr) {}
-
-    PropertyTreeState(
-        const TransformPaintPropertyNode* transform,
-        const ClipPaintPropertyNode* clip,
-        const EffectPaintPropertyNode* effect)
-    : transform(transform), clip(clip), effect(effect) {}
-
-    RefPtr<const TransformPaintPropertyNode> transform;
-    RefPtr<const ClipPaintPropertyNode> clip;
-    RefPtr<const EffectPaintPropertyNode> effect;
-};
-
-template <class A>
-unsigned propertyTreeNodeDepth(const A* node)
-{
-    unsigned depth = 0;
-    while (node) {
-        depth++;
-        node = node->parent();
-    }
-    return depth;
-}
-
-template <class A>
-const A* propertyTreeNearestCommonAncestor(const A* a, const A* b)
-{
-    // Measure both depths.
-    unsigned depthA = propertyTreeNodeDepth<A>(a);
-    unsigned depthB = propertyTreeNodeDepth<A>(b);
-
-    // Make it so depthA >= depthB.
-    if (depthA < depthB) {
-        std::swap(a, b);
-        std::swap(depthA, depthB);
-    }
-
-    // Make it so depthA == depthB.
-    while (depthA > depthB) {
-        a = a->parent();
-        depthA--;
-    }
-
-    // Walk up until we find the ancestor.
-    while (a != b) {
-        a = a->parent();
-        b = b->parent();
-    }
-    return a;
-}
-
-} // namespace blink
-
-#endif // PropertyTreeState_h