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

third_party/WebKit/Source/platform/graphics/compositing/PaintArtifactCompositor.cpp

Index: third_party/WebKit/Source/platform/graphics/compositing/PaintArtifactCompositor.cpp
diff --git a/third_party/WebKit/Source/platform/graphics/compositing/PaintArtifactCompositor.cpp b/third_party/WebKit/Source/platform/graphics/compositing/PaintArtifactCompositor.cpp
index 85faa47843757739f06908f6240e1c56126d6cf3..6b72cac58ab5b98f4c1bf032ca6011f1161e6467 100644
--- a/third_party/WebKit/Source/platform/graphics/compositing/PaintArtifactCompositor.cpp
+++ b/third_party/WebKit/Source/platform/graphics/compositing/PaintArtifactCompositor.cpp
@@ -4,6 +4,9 @@
 
 #include "platform/graphics/compositing/PaintArtifactCompositor.h"
 
+#include <algorithm>
+#include <memory>
+#include <utility>
 #include "cc/layers/content_layer_client.h"
 #include "cc/layers/layer.h"
 #include "cc/layers/picture_layer.h"
@@ -40,9 +43,6 @@
 #include "wtf/Allocator.h"
 #include "wtf/Noncopyable.h"
 #include "wtf/PtrUtil.h"
-#include <algorithm>
-#include <memory>
-#include <utility>
 
 namespace blink {
 
@@ -671,7 +671,8 @@ void PaintArtifactCompositor::update(
     const PaintArtifact& paintArtifact,
     RasterInvalidationTrackingMap<const PaintChunk>* rasterChunkInvalidations,
     bool storeDebugInfo,
-    GeometryMapper& geometryMapper) {
+    GeometryMapper& geometryMapper,
+    ScrollClientMap& scrollClients) {
 #ifndef NDEBUG
   storeDebugInfo = true;
 #endif
@@ -723,8 +724,16 @@ void PaintArtifactCompositor::update(
     layer->SetTransformTreeIndex(transformId);
     layer->SetClipTreeIndex(clipId);
     layer->SetEffectTreeIndex(effectId);
-    layer->SetScrollTreeIndex(propertyTreeManager.ensureCompositorScrollNode(
-        transform->findEnclosingScrollNode()));
+    propertyTreeManager.updateLayerScrollMapping(layer.get(), transform);
+
+    if (transform->isScrollTranslation()) {
+      auto scrollClientIt = scrollClients.find(transform->scrollNode());
+      if (scrollClientIt != scrollClients.end()) {
+        layer->set_did_scroll_callback(
+            base::Bind(&blink::WebLayerScrollClient::didScroll,
+                       base::Unretained(scrollClientIt->value)));
+      }
+    }
 
     layer->SetShouldCheckBackfaceVisibility(pendingLayer.backfaceHidden);