Fix position of layer with floating ancestor within inline parent layer

third_party/WebKit/Source/core/paint/PaintLayer.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011, 2012 Apple Inc. All rights
  * reserved.
  *
  * Portions are Copyright (C) 1998 Netscape Communications Corporation.
  *
  * Other contributors:
  *   Robert O'Callahan <roc+@cs.cmu.edu>
  *   David Baron <dbaron@fas.harvard.edu>
  *   Christian Biesinger <cbiesinger@web.de>
@@ skipping 903 matching lines @@
       transformAncestor() ? transformAncestor()->layoutObject() : nullptr,
       transformState, 0);
   transformState.flatten();
   return LayoutPoint(transformState.lastPlanarPoint());
 }
 
 PaintLayer* PaintLayer::compositingContainer() const {
   if (!stackingNode()->isStacked()) {
     // Floats have special painting order, which has complicated semantics.
     // See the comments around FloatObject::setShouldPaint.
     if (!isSelfPaintingLayer() && m_layoutObject->isFloating() &&

[chrishtr, 2017/03/22 23:23:33]

Do you need to fix this one too?

[Xianzhu, 2017/03/22 23:25:17]

I would like to keep this as-is, as the compositing issue was not new.

         m_layoutObject->parent() &&
         !m_layoutObject->parent()->isLayoutBlockFlow())
       return m_layoutObject->containingBlock()->enclosingLayer();
 
     return parent();
   }
   if (PaintLayerStackingNode* ancestorStackingNode =
           stackingNode()->ancestorStackingContextNode())
     return ancestorStackingNode->layer();
   return nullptr;
@@ skipping 479 matching lines @@
   if (position == FixedPosition &&
       (!ancestorLayer || ancestorLayer == layoutObject->view()->layer())) {
     // If the fixed layer's container is the root, just add in the offset of the
     // view. We can obtain this by calling localToAbsolute() on the LayoutView.
     FloatPoint absPos = layoutObject->localToAbsolute();
     location += LayoutSize(absPos.x(), absPos.y());
     return ancestorLayer;
   }
 
   PaintLayer* parentLayer = nullptr;
-  if (position == AbsolutePosition || position == FixedPosition ||
-      (layoutObject->isFloating() && layoutObject->parent() &&
-       !layoutObject->parent()->isLayoutBlockFlow())) {
+  bool isOutOfFlowPositioned =
+      position == AbsolutePosition || position == FixedPosition;
+  if (isOutOfFlowPositioned ||
+      // If the parent layer is not a block, there might be floating objects
+      // between this layer (included) and parent layer which need to escape the
+      // inline parent to find the actual containing layer through the
+      // containing block chain.
+      (layer->parent() && !layer->parent()->layoutObject()->isLayoutBlock())) {
     bool foundAncestorFirst = false;
-    if (layoutObject->isFloating()) {
+    if (!isOutOfFlowPositioned) {
       Optional<LayoutObject::AncestorSkipInfo> skipInfo;
       if (ancestorLayer)
         skipInfo.emplace(ancestorLayer->layoutObject());
-      if (auto* containingBlock = layoutObject->containingBlock(
-              ancestorLayer ? &*skipInfo : nullptr)) {
-        parentLayer = containingBlock->enclosingLayer();
-        foundAncestorFirst = ancestorLayer && skipInfo->ancestorSkipped();
+
+      const LayoutObject* object = layoutObject;
+      while (auto* container =
+                 object->container(ancestorLayer ? &*skipInfo : nullptr)) {
+        foundAncestorFirst |= ancestorLayer && skipInfo->ancestorSkipped();
+        if (container->hasLayer()) {
+          parentLayer = toLayoutBoxModelObject(container)->layer();
+          break;
+        }
+        object = container;
       }
     } else {
       parentLayer = layer->containingLayerForOutOfFlowPositioned(
           ancestorLayer, &foundAncestorFirst);
     }
 
     if (foundAncestorFirst) {
       // Found ancestorLayer before the container of the out-of-flow object, so
       // compute offset of both relative to the container and subtract.
 
@@ skipping 1774 matching lines @@
 }
 
 void showLayerTree(const blink::LayoutObject* layoutObject) {
   if (!layoutObject) {
     LOG(INFO) << "Cannot showLayerTree. Root is (nil)";
     return;
   }
   showLayerTree(layoutObject->enclosingLayer());
 }
 #endif