Adapt and reland old position sticky implementation

third_party/WebKit/Source/core/layout/compositing/CompositingInputsUpdater.cpp

Index: third_party/WebKit/Source/core/layout/compositing/CompositingInputsUpdater.cpp
diff --git a/third_party/WebKit/Source/core/layout/compositing/CompositingInputsUpdater.cpp b/third_party/WebKit/Source/core/layout/compositing/CompositingInputsUpdater.cpp
index 5fe741f854763cfcd01ec40b6d637b6c10f2e528..52fc69583cee0420e45c17c314428c8d8f4420e4 100644
--- a/third_party/WebKit/Source/core/layout/compositing/CompositingInputsUpdater.cpp
+++ b/third_party/WebKit/Source/core/layout/compositing/CompositingInputsUpdater.cpp
@@ -4,7 +4,9 @@
 
 #include "core/layout/compositing/CompositingInputsUpdater.h"
 
+#include "core/frame/FrameView.h"
 #include "core/layout/LayoutBlock.h"
+#include "core/layout/LayoutView.h"
 #include "core/layout/compositing/CompositedLayerMapping.h"
 #include "core/layout/compositing/PaintLayerCompositor.h"
 #include "core/paint/PaintLayer.h"
@@ -25,7 +27,7 @@ CompositingInputsUpdater::~CompositingInputsUpdater()
 void CompositingInputsUpdater::update()
 {
     TRACE_EVENT0("blink", "CompositingInputsUpdater::update");
-    updateRecursive(m_rootLayer, DoNotForceUpdate, AncestorInfo());
+    updateRecursive(m_rootLayer, DoNotForceUpdate, AncestorInfo(m_rootLayer));
 }
 
 static const PaintLayer* findParentLayerOnClippingContainerChain(const PaintLayer* layer)
@@ -136,9 +138,14 @@ void CompositingInputsUpdater::updateRecursive(PaintLayer* layer, UpdateType upd
                 properties.clippingContainer = parentHasClipRelatedProperty ? parentLayerOnClippingContainerChain->layoutObject() : parentLayerOnClippingContainerChain->clippingContainer();
             }
 
+            const LayoutObject* containingBlock = layer->layoutObject()->containingBlock();
+            const PaintLayer* parentLayerOnContainingBlockChain = findParentLayerOnContainingBlockChain(containingBlock);
+
+            rareProperties.ancestorOverflowLayer = parentLayerOnContainingBlockChain->ancestorOverflowLayer();
+            if (parentLayerOnContainingBlockChain->layoutObject()->hasOverflowClip())
+                rareProperties.ancestorOverflowLayer = parentLayerOnContainingBlockChain;
+
             if (info.lastScrollingAncestor) {
-                const LayoutObject* containingBlock = layer->layoutObject()->containingBlock();
-                const PaintLayer* parentLayerOnContainingBlockChain = findParentLayerOnContainingBlockChain(containingBlock);
 
                 rareProperties.ancestorScrollingLayer = parentLayerOnContainingBlockChain->ancestorScrollingLayer();
                 if (parentLayerOnContainingBlockChain->scrollsOverflow())
@@ -155,6 +162,16 @@ void CompositingInputsUpdater::updateRecursive(PaintLayer* layer, UpdateType upd
                     && !info.ancestorStackingContext->layoutObject()->isDescendantOf(rareProperties.ancestorScrollingLayer->layoutObject()))
                     rareProperties.scrollParent = rareProperties.ancestorScrollingLayer;
             }
+
+            if (layer->layoutObject()->style()->position() == StickyPosition) {
+                if (info.lastOverflowLayer->isRootLayer())
+                    layer->layoutObject()->view()->frameView()->addViewportConstrainedObject(layer->layoutObject());
+                else
+                    layer->layoutObject()->view()->frameView()->removeViewportConstrainedObject(layer->layoutObject());
+                layer->layoutObject()->updateStickyPositionConstraints(info.lastOverflowLayer);
+            }
+        } else {
+            rareProperties.ancestorOverflowLayer = info.lastOverflowLayer;
         }
 
         layer->updateAncestorDependentCompositingInputs(properties, rareProperties, info.hasAncestorWithClipPath);
@@ -163,6 +180,9 @@ void CompositingInputsUpdater::updateRecursive(PaintLayer* layer, UpdateType upd
     if (layer->stackingNode()->isStackingContext())
         info.ancestorStackingContext = layer;
 
+    if (layer->layoutObject()->hasOverflowClip())
+        info.lastOverflowLayer = layer;
+
     if (layer->scrollsOverflow())
         info.lastScrollingAncestor = layer;