Improve performance of GeometryMapper cache.

third_party/WebKit/Source/platform/graphics/paint/ClipPaintPropertyNode.cpp

Index: third_party/WebKit/Source/platform/graphics/paint/ClipPaintPropertyNode.cpp
diff --git a/third_party/WebKit/Source/platform/graphics/paint/ClipPaintPropertyNode.cpp b/third_party/WebKit/Source/platform/graphics/paint/ClipPaintPropertyNode.cpp
index 0a718c46c57d4c9b666cbfe9bc246b3a99e812fe..49c9035a3b7cbf06e920ffcdd0f0127059fb56c2 100644
--- a/third_party/WebKit/Source/platform/graphics/paint/ClipPaintPropertyNode.cpp
+++ b/third_party/WebKit/Source/platform/graphics/paint/ClipPaintPropertyNode.cpp
@@ -9,6 +9,22 @@
 
 namespace blink {
 
+// All clip caches invalidate themselves by tracking a local cache generation,
+// and invalidating their cache if their cache generation disagrees with
+// s_clipCacheGeneration.
+static unsigned s_clipCacheGeneration = 0;
+
+ClipPaintPropertyNode::ClipPaintPropertyNode(
+    PassRefPtr<const ClipPaintPropertyNode> parent,
+    PassRefPtr<const TransformPaintPropertyNode> localTransformSpace,
+    const FloatRoundedRect& clipRect,
+    CompositingReasons directCompositingReasons)
+    : m_parent(parent),
+      m_localTransformSpace(localTransformSpace),
+      m_clipRect(clipRect),
+      m_directCompositingReasons(directCompositingReasons),
+      m_cacheGeneration(s_clipCacheGeneration) {}
+
 ClipPaintPropertyNode* ClipPaintPropertyNode::root() {
   DEFINE_STATIC_REF(ClipPaintPropertyNode, root,
                     (ClipPaintPropertyNode::create(
@@ -34,4 +50,44 @@ String ClipPaintPropertyNode::toTreeString() const {
 
 #endif
 
+void ClipPaintPropertyNode::clearCache() {
+  s_clipCacheGeneration++;
+}
+
+Vector<ClipPaintPropertyNode::ClipCacheEntry>*
+ClipPaintPropertyNode::getClipCacheEntries() {
+  if (m_cacheGeneration != s_clipCacheGeneration || !m_clipCache) {
+    m_clipCache.reset(new Vector<ClipCacheEntry>);
+    m_cacheGeneration = s_clipCacheGeneration;
+  }
+
+  return m_clipCache.get();
+}
+
+const FloatClipRect* ClipPaintPropertyNode::getCachedClip(
+    const ClipAndTransform& clipAndTransform) const {
+  auto* clipCacheEntries =
+      const_cast<ClipPaintPropertyNode*>(this)->getClipCacheEntries();
+  for (const auto& entry : *clipCacheEntries) {
+    if (entry.clipAndTransform == clipAndTransform) {
+      return &entry.clipRect;
+    }
+  }
+  return nullptr;
+}
+
+void ClipPaintPropertyNode::setCachedClip(
+    const ClipAndTransform& clipAndTransform,
+    const FloatClipRect& clip) const {
+  auto* clipCacheEntries =
+      const_cast<ClipPaintPropertyNode*>(this)->getClipCacheEntries();
+#if DCHECK_IS_ON
+  for (const auto& entry : clipCachEntries) {
+    if (entry.clipAndTransform == clipAndTransform)
+      DCHECK(false);  // There should be no existing entry.
+  }
+#endif
+  clipCacheEntries->push_back(ClipCacheEntry(clipAndTransform, clip));
+}
+
 }  // namespace blink