End-to-end prototype of compositor scrolling with slimming paint v2

third_party/WebKit/Source/core/frame/FrameView.cpp

 /*
  * Copyright (C) 1998, 1999 Torben Weis <weis@kde.org>
  *                     1999 Lars Knoll <knoll@kde.org>
  *                     1999 Antti Koivisto <koivisto@kde.org>
  *                     2000 Dirk Mueller <mueller@kde.org>
  * Copyright (C) 2004, 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.
  *           (C) 2006 Graham Dennis (graham.dennis@gmail.com)
  *           (C) 2006 Alexey Proskuryakov (ap@nypop.com)
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
@@ skipping 3140 matching lines @@
     return;
 
   if (!m_paintArtifactCompositor) {
     m_paintArtifactCompositor = PaintArtifactCompositor::create();
     page->chromeClient().attachRootLayer(
         m_paintArtifactCompositor->getWebLayer(), &frame());
   }
 
   SCOPED_BLINK_UMA_HISTOGRAM_TIMER("Blink.Compositing.UpdateTime");
 
+  // TODO(pdr): This map should be cached.
+  PaintArtifactCompositor::ScrollClientMap scrollClientMap;
+  if (m_scrollableAreas) {
+    for (auto scrollableArea : *m_scrollableAreas) {
+      const auto* box = scrollableArea->layoutBox();
+      if (!box)
+        continue;
+      const auto* properties = box->paintProperties();
+      if (!properties)
+        continue;
+      const auto* scrollTranslation = properties->scrollTranslation();
+      if (!scrollTranslation)
+        continue;
+      const auto* scrollNode = scrollTranslation->scrollNode();
+      scrollClientMap.set(scrollNode, scrollableArea.get());
+    }
+  }
+  if (const auto* scrollTranslationNode = scrollTranslation()) {
+    if (auto* scrollableArea = getScrollableArea())
+      scrollClientMap.set(scrollTranslationNode->scrollNode(), scrollableArea);
+  }
+
   DCHECK(m_geometryMapper.get());
   m_paintArtifactCompositor->update(
       m_paintController->paintArtifact(),
       m_paintController->paintChunksRasterInvalidationTrackingMap(),
-      m_isStoringCompositedLayerDebugInfo, *m_geometryMapper);
+      m_isStoringCompositedLayerDebugInfo, *m_geometryMapper, scrollClientMap);
 }
 
 std::unique_ptr<JSONObject> FrameView::compositedLayersAsJSON(
     LayerTreeFlags flags) {
   return frame()
       .localFrameRoot()
       ->view()
       ->m_paintArtifactCompositor->layersAsJSON(flags);
 }
 
@@ skipping 1923 matching lines @@
     std::unique_ptr<CompositorAnimationTimeline> timeline) {
   m_animationTimeline = std::move(timeline);
 }
 
 void FrameView::setAnimationHost(
     std::unique_ptr<CompositorAnimationHost> host) {
   m_animationHost = std::move(host);
 }
 
 }  // namespace blink