Fix focus navigation for nested slot case

third_party/WebKit/Source/core/page/FocusController.cpp

Index: third_party/WebKit/Source/core/page/FocusController.cpp
diff --git a/third_party/WebKit/Source/core/page/FocusController.cpp b/third_party/WebKit/Source/core/page/FocusController.cpp
index 180f66033404f3c61646f90656a2bfed7c524918..bcc8233a6c687914aba41f571c2009ed7d97c475 100644
--- a/third_party/WebKit/Source/core/page/FocusController.cpp
+++ b/third_party/WebKit/Source/core/page/FocusController.cpp
@@ -71,6 +71,37 @@ inline bool isShadowInsertionPointFocusScopeOwner(Element& element) {
          toHTMLShadowElement(element).olderShadowRoot();
 }
 
+inline bool hasCustomFocusLogic(const Element& element) {
+  return element.isHTMLElement() &&
+         toHTMLElement(element).hasCustomFocusLogic();
+}
+
+inline bool isShadowHostWithoutCustomFocusLogic(const Element& element) {
+  return isShadowHost(element) && !hasCustomFocusLogic(element);
+}
+
+inline bool isNonKeyboardFocusableShadowHost(const Element& element) {
+  return isShadowHostWithoutCustomFocusLogic(element) &&
+         !(element.shadowRootIfV1() ? element.isFocusable()
+                                    : element.isKeyboardFocusable());
+}
+
+inline bool isKeyboardFocusableShadowHost(const Element& element) {
+  return isShadowHostWithoutCustomFocusLogic(element) &&
+         element.isKeyboardFocusable();
+}
+
+inline bool isNonFocusableFocusScopeOwner(Element& element) {
+  return isNonKeyboardFocusableShadowHost(element) ||
+         isShadowInsertionPointFocusScopeOwner(element) ||
+         isHTMLSlotElement(element);
+}
+
+inline bool isShadowHostDelegatesFocus(const Element& element) {
+  return element.authorShadowRoot() &&
+         element.authorShadowRoot()->delegatesFocus();
+}
+
 class ScopedFocusNavigation {
   STACK_ALLOCATED();
 
@@ -203,11 +234,25 @@ void ScopedFocusNavigation::moveToLast() {
       HeapVector<Member<Node>> assignedNodes = m_rootSlot->assignedNodes();
       for (auto assignedNode = assignedNodes.rbegin();
            assignedNode != assignedNodes.rend(); ++assignedNode) {
-        if ((*assignedNode)->isElementNode()) {
-          m_current =
-              ElementTraversal::lastWithinOrSelf(*toElement(*assignedNode));
-          break;
+        if (!(*assignedNode)->isElementNode())
+          continue;
+
+        Element* last = ElementTraversal::lastWithin(*toElement(*assignedNode));
+        if (!last) {
+          m_current = toElement(*assignedNode);
+        } else {
+          while (last) {
+            Element* ancestor =
+                SlotScopedTraversal::nearestAncestorAssignedToSlot(*last);
+            DCHECK(ancestor);
+            if (ancestor == *assignedNode)
+              break;
+            last = ancestor->parentElement();
+          }
+          DCHECK(last);
+          m_current = last;
         }
+        break;
       }
     } else {
       Element* last = ElementTraversal::lastWithin(*m_rootSlot);
@@ -380,37 +425,6 @@ inline void dispatchEventsOnWindowAndFocusedElement(Document* document,
   }
 }
 
-inline bool hasCustomFocusLogic(const Element& element) {
-  return element.isHTMLElement() &&
-         toHTMLElement(element).hasCustomFocusLogic();
-}
-
-inline bool isShadowHostWithoutCustomFocusLogic(const Element& element) {
-  return isShadowHost(element) && !hasCustomFocusLogic(element);
-}
-
-inline bool isNonKeyboardFocusableShadowHost(const Element& element) {
-  return isShadowHostWithoutCustomFocusLogic(element) &&
-         !(element.shadowRootIfV1() ? element.isFocusable()
-                                    : element.isKeyboardFocusable());
-}
-
-inline bool isKeyboardFocusableShadowHost(const Element& element) {
-  return isShadowHostWithoutCustomFocusLogic(element) &&
-         element.isKeyboardFocusable();
-}
-
-inline bool isNonFocusableFocusScopeOwner(Element& element) {
-  return isNonKeyboardFocusableShadowHost(element) ||
-         isShadowInsertionPointFocusScopeOwner(element) ||
-         isHTMLSlotElement(element);
-}
-
-inline bool isShadowHostDelegatesFocus(const Element& element) {
-  return element.authorShadowRoot() &&
-         element.authorShadowRoot()->delegatesFocus();
-}
-
 inline int adjustedTabIndex(Element& element) {
   return (isNonKeyboardFocusableShadowHost(element) ||
           isShadowInsertionPointFocusScopeOwner(element))