[LayoutNG] Adapt accessibility module to LayoutNG

This patch adapts accessibility module to LayoutNG by:
 * Make |AbstractInlineTextBox| as an interface like class and implements legacy
 version |LegacyAbstractInlineTextBox| using InlineTextBox and LayoutNG
 version |NGAbstractInlineTextBox| using NGPaintFragment.
 * Make |AXLayoutObject| to handle |LayoutNGListMarker|
   - |LayoutListMarker| has no children.
   - |LayoutNGListMarker| is a container of list marker.
 * Make |AXLayoutObject::ComputeAccessibilityIsIgnored()| to handle LayoutNG
 block flow to check empty block flow.
 * Make |NGPaintFragment::FragmentRange::iterator| to work with |std::next()|
 * Intrdouce LayoutText::GetFirstLetterPart() for ease of getting layout object
  for first-letter part from layout object for remaining part.

Following patch will implements NGAbstractInlineTextBox::CharacterWidths()

The doc,https://bit.ly/2kUEFZy, contains study and change details.

TBR=dmazzoni@chromium.org

Bug: 714962
Cq-Include-Trybots: luci.chromium.try:linux_layout_tests_layout_ng;luci.chromium.try:linux_layout_tests_slimming_paint_v2;master.tryserver.blink:linux_trusty_blink_rel
Change-Id: Iae25e8a7d7e6be0c7478470c690e081084476e85
Reviewed-on: https://chromium-review.googlesource.com/1104082
Commit-Queue: Yoshifumi Inoue <yosin@chromium.org>
Reviewed-by: Yoshifumi Inoue <yosin@chromium.org>
Reviewed-by: Koji Ishii <kojii@chromium.org>
Cr-Commit-Position: refs/heads/master@{#569235}

third_party/WebKit/LayoutTests/FlagExpectations/enable-blink-features=LayoutNG

@@ -23,6 +23,11 @@ crbug.com/591099 fast/block/child-not-removed-from-parent-lineboxes-crash.html [
 # https://cs.chromium.org/chromium/src/third_party/blink/renderer/core/layout/layout_block.cc?l=1372&rcl=0e081149ecd6a83f6289e3aee5797936008a1e10
 crbug.com/591099 fast/block/marquee-width-shrinks-to-fit-in-fixed-size-container.html [ Failure ]
 
+# Whitespace differences only
+crbug.com/854889 accessibility/canvas-fallback-content-2.html [ Failure ]
+crbug.com/854889 accessibility/css-generated-content.html [ Failure Pass ]
+crbug.com/854889 accessibility/css-styles.html [ Failure ]
+
 # Hit test failure due to vertical-rl writing mode
 crbug.com/851075 fast/writing-mode/vertical-inline-block-hittest.html [ Failure ]
 
@@ -53,46 +58,9 @@ crbug.com/591099 external/wpt/css/css-writing-modes/two-levels-of-orthogonal-flo
 crbug.com/591099 fast/dom/inner-text-first-letter.html [ Pass ]
 
 # New failures are appended below by the script.
-crbug.com/714962 accessibility/adjacent-continuations-cause-assertion-failure.html [ Failure ]
-crbug.com/591099 accessibility/aom-relation-list-properties.html [ Failure ]
-crbug.com/591099 accessibility/aria-labelledby-stay-within.html [ Failure ]
-crbug.com/591099 accessibility/aria-owns.html [ Failure ]
-crbug.com/591099 accessibility/aria-tab-roles.html [ Failure ]
-crbug.com/714962 accessibility/aria-tables.html [ Failure ]
-crbug.com/714962 accessibility/background-color.html [ Failure ]
-crbug.com/714962 accessibility/bounds-calc.html [ Failure ]
-crbug.com/591099 accessibility/canvas-fallback-content-2.html [ Timeout ]
-crbug.com/714962 accessibility/css-first-letter-children.html [ Failure ]
-crbug.com/591099 accessibility/css-generated-content.html [ Failure ]
-crbug.com/591099 accessibility/css-styles.html [ Failure ]
-crbug.com/591099 accessibility/default-language.html [ Failure ]
-crbug.com/591099 accessibility/disabled-controls.html [ Failure ]
-crbug.com/714962 accessibility/div-within-anchors-causes-crash.html [ Failure ]
-crbug.com/714962 accessibility/dl-role.html [ Failure ]
-crbug.com/714962 accessibility/first-letter-text-transform-causes-crash.html [ Failure ]
-crbug.com/591099 accessibility/focusable-div.html [ Failure ]
-crbug.com/591099 accessibility/focusable-span.html [ Failure ]
-crbug.com/714962 accessibility/in-page-link-target.html [ Failure ]
 crbug.com/591099 accessibility/inline-text-bidi-bounds-for-range.html [ Failure ]
 crbug.com/714962 accessibility/inline-text-bounds-for-range-br.html [ Failure ]
 crbug.com/591099 accessibility/inline-text-bounds-for-range.html [ Failure ]
-crbug.com/591099 accessibility/inline-text-change-style.html [ Failure ]
-crbug.com/591099 accessibility/inline-text-changes.html [ Failure ]
-crbug.com/591099 accessibility/inline-text-word-boundaries.html [ Failure ]
-crbug.com/591099 accessibility/language-attribute-and-meta-tag.html [ Failure ]
-crbug.com/591099 accessibility/language-meta-tag-dynamically-changing.html [ Failure ]
-crbug.com/714962 accessibility/legend.html [ Failure ]
-crbug.com/591099 accessibility/listitem-presentation-inherited.html [ Failure ]
-crbug.com/591099 accessibility/name-calc-aria-owns.html [ Failure ]
-crbug.com/591099 accessibility/presentation-owned-elements.html [ Failure ]
-crbug.com/591099 accessibility/role-attribute.html [ Failure ]
-crbug.com/591099 accessibility/role-change.html [ Failure ]
-crbug.com/714962 accessibility/selection-events.html [ Failure ]
-crbug.com/714962 accessibility/set-selection-link.html [ Failure ]
-crbug.com/591099 accessibility/table-caption.html [ Failure ]
-crbug.com/591099 accessibility/table-header-column-row.html [ Failure ]
-crbug.com/714962 accessibility/table-with-empty-thead-causes-crash.html [ Failure ]
-crbug.com/591099 accessibility/table-with-presentation-role.html [ Failure ]
 crbug.com/591099 animations/cross-fade-list-style-image.html [ Failure ]
 crbug.com/591099 animations/rotate-transform-equivalent.html [ Failure ]
 crbug.com/714962 compositing/background-color/view-blending-base-background.html [ Failure ]

third_party/blink/renderer/core/layout/BUILD.gn

@@ -323,6 +323,8 @@ blink_core_sources("layout") {
     "ng/geometry/ng_static_position.cc",
     "ng/geometry/ng_static_position.h",
     "ng/inline/empty_offset_mapping_builder.h",
+    "ng/inline/ng_abstract_inline_text_box.cc",
+    "ng/inline/ng_abstract_inline_text_box.h",
     "ng/inline/ng_baseline.cc",
     "ng/inline/ng_baseline.h",
     "ng/inline/ng_bidi_paragraph.cc",

third_party/blink/renderer/core/layout/layout_object.cc

@@ -4029,14 +4029,7 @@ const LayoutObject* AssociatedLayoutObjectOf(const Node& node,
     if (static_cast<unsigned>(offset_in_node) >= threshold)
       return layout_object;
   }
-  LayoutObject* first_letter_layout_object =
-      layout_text_fragment->GetFirstLetterPseudoElement()->GetLayoutObject();
-  // TODO(yosin): We're not sure when |firstLetterLayoutObject| has
-  // multiple child layout object.
-  LayoutObject* child = first_letter_layout_object->SlowFirstChild();
-  CHECK(child && child->IsText());
-  DCHECK_EQ(child, first_letter_layout_object->SlowLastChild());
-  return child;
+  return layout_text_fragment->GetFirstLetterPart();
 }
 
 bool LayoutObject::CanBeSelectionLeaf() const {

third_party/blink/renderer/core/layout/layout_text.cc

@@ -50,6 +50,7 @@
 #include "third_party/blink/renderer/core/layout/line/glyph_overflow.h"
 #include "third_party/blink/renderer/core/layout/line/inline_text_box.h"
 #include "third_party/blink/renderer/core/layout/ng/geometry/ng_logical_rect.h"
+#include "third_party/blink/renderer/core/layout/ng/inline/ng_abstract_inline_text_box.h"
 #include "third_party/blink/renderer/core/layout/ng/inline/ng_inline_fragment_traversal.h"
 #include "third_party/blink/renderer/core/layout/ng/inline/ng_inline_node.h"
 #include "third_party/blink/renderer/core/layout/ng/inline/ng_offset_mapping.h"
@@ -2214,8 +2215,18 @@ void LayoutText::MomentarilyRevealLastTypedCharacter(
 }
 
 scoped_refptr<AbstractInlineTextBox> LayoutText::FirstAbstractInlineTextBox() {
-  return AbstractInlineTextBox::GetOrCreate(LineLayoutText(this),
-                                            FirstTextBox());
+  if (RuntimeEnabledFeatures::LayoutNGEnabled()) {
+    LayoutObject* const first_letter_part = GetFirstLetterPart();
+    auto fragments = NGPaintFragment::InlineFragmentsFor(
+        first_letter_part ? first_letter_part : this);
+    if (!fragments.IsEmpty() &&
+        fragments.IsInLayoutNGInlineFormattingContext()) {
+      return NGAbstractInlineTextBox::GetOrCreate(LineLayoutText(this),
+                                                  **fragments.begin());
+    }
+  }
+  return LegacyAbstractInlineTextBox::GetOrCreate(LineLayoutText(this),
+                                                  FirstTextBox());
 }
 
 void LayoutText::InvalidateDisplayItemClients(

third_party/blink/renderer/core/layout/layout_text.h

@@ -94,6 +94,9 @@ class CORE_EXPORT LayoutText : public LayoutObject {
   virtual unsigned TextStartOffset() const { return 0; }
   String PlainText() const;
 
+  // Returns first letter part of |LayoutTextFragment|.
+  virtual LayoutText* GetFirstLetterPart() { return nullptr; }
+
   InlineTextBox* CreateInlineTextBox(int start, unsigned short length);
   void DirtyOrDeleteLineBoxesIfNeeded(bool full_layout);
   void DirtyLineBoxes();
@@ -201,6 +204,9 @@ class CORE_EXPORT LayoutText : public LayoutObject {
 
   const InlineTextBoxList& TextBoxes() const { return text_boxes_; }
 
+  // Returns first |InlineTextBox| produces for associated |Node|.
+  // Note: When |this| is remaining part of ::first-letter, this function
+  // returns first-letter part of |InlineTextBox| instead of remaining part.
   InlineTextBox* FirstTextBox() const { return text_boxes_.First(); }
   InlineTextBox* LastTextBox() const { return text_boxes_.Last(); }
 

third_party/blink/renderer/core/layout/layout_text_fragment.cc

@@ -160,6 +160,19 @@ Text* LayoutTextFragment::AssociatedTextNode() const {
   return (node && node->IsTextNode()) ? ToText(node) : nullptr;
 }
 
+LayoutText* LayoutTextFragment::GetFirstLetterPart() {
+  if (!is_remaining_text_layout_object_)
+    return nullptr;
+  // Node: We assume first letter pseudo element has only one child and it
+  // is LayoutTextFragment.
+  LayoutObject* const first_letter_container =
+      GetFirstLetterPseudoElement()->GetLayoutObject();
+  LayoutObject* const child = first_letter_container->SlowFirstChild();
+  CHECK(child->IsText());
+  DCHECK_EQ(child, first_letter_container->SlowLastChild());
+  return ToLayoutTextFragment(child);
+}
+
 void LayoutTextFragment::UpdateHitTestResult(HitTestResult& result,
                                              const LayoutPoint& point) const {
   if (result.InnerNode())

third_party/blink/renderer/core/layout/layout_text_fragment.h

@@ -94,6 +94,7 @@ class CORE_EXPORT LayoutTextFragment final : public LayoutText {
   }
 
   Text* AssociatedTextNode() const;
+  LayoutText* GetFirstLetterPart() override;
 
  protected:
   void WillBeDestroyed() override;

third_party/blink/renderer/core/layout/line/abstract_inline_text_box.cc

@@ -37,35 +37,45 @@
 
 namespace blink {
 
-AbstractInlineTextBox::InlineToAbstractInlineTextBoxHashMap*
-    AbstractInlineTextBox::g_abstract_inline_text_box_map_ = nullptr;
+AbstractInlineTextBox::AbstractInlineTextBox(LineLayoutText line_layout_item)
+    : line_layout_item_(line_layout_item) {}
 
-scoped_refptr<AbstractInlineTextBox> AbstractInlineTextBox::GetOrCreate(
+AbstractInlineTextBox::~AbstractInlineTextBox() {
+  DCHECK(!line_layout_item_);
+}
+
+// ----
+
+LegacyAbstractInlineTextBox::InlineToLegacyAbstractInlineTextBoxHashMap*
+    LegacyAbstractInlineTextBox::g_abstract_inline_text_box_map_ = nullptr;
+
+scoped_refptr<AbstractInlineTextBox> LegacyAbstractInlineTextBox::GetOrCreate(
     LineLayoutText line_layout_text,
     InlineTextBox* inline_text_box) {
   if (!inline_text_box)
     return nullptr;
 
-  if (!g_abstract_inline_text_box_map_)
+  if (!g_abstract_inline_text_box_map_) {
     g_abstract_inline_text_box_map_ =
-        new InlineToAbstractInlineTextBoxHashMap();
+        new InlineToLegacyAbstractInlineTextBoxHashMap();
+  }
 
-  InlineToAbstractInlineTextBoxHashMap::const_iterator it =
+  InlineToLegacyAbstractInlineTextBoxHashMap::const_iterator it =
       g_abstract_inline_text_box_map_->find(inline_text_box);
   if (it != g_abstract_inline_text_box_map_->end())
     return it->value;
 
   scoped_refptr<AbstractInlineTextBox> obj = base::AdoptRef(
-      new AbstractInlineTextBox(line_layout_text, inline_text_box));
+      new LegacyAbstractInlineTextBox(line_layout_text, inline_text_box));
   g_abstract_inline_text_box_map_->Set(inline_text_box, obj);
   return obj;
 }
 
-void AbstractInlineTextBox::WillDestroy(InlineTextBox* inline_text_box) {
+void LegacyAbstractInlineTextBox::WillDestroy(InlineTextBox* inline_text_box) {
   if (!g_abstract_inline_text_box_map_)
     return;
 
-  InlineToAbstractInlineTextBoxHashMap::const_iterator it =
+  InlineToLegacyAbstractInlineTextBoxHashMap::const_iterator it =
       g_abstract_inline_text_box_map_->find(inline_text_box);
   if (it != g_abstract_inline_text_box_map_->end()) {
     it->value->Detach();
@@ -73,51 +83,62 @@ void AbstractInlineTextBox::WillDestroy(InlineTextBox* inline_text_box) {
   }
 }
 
-AbstractInlineTextBox::~AbstractInlineTextBox() {
-  DCHECK(!line_layout_item_);
+LegacyAbstractInlineTextBox::LegacyAbstractInlineTextBox(
+    LineLayoutText line_layout_item,
+    InlineTextBox* inline_text_box)
+    : AbstractInlineTextBox(line_layout_item),
+      inline_text_box_(inline_text_box) {}
+
+LegacyAbstractInlineTextBox::~LegacyAbstractInlineTextBox() {
   DCHECK(!inline_text_box_);
 }
 
 void AbstractInlineTextBox::Detach() {
+  DCHECK(GetLineLayoutItem());
   if (Node* node = GetNode()) {
     if (AXObjectCache* cache = node->GetDocument().ExistingAXObjectCache())
       cache->Remove(this);
   }
 
   line_layout_item_ = LineLayoutText(nullptr);
+}
+
+void LegacyAbstractInlineTextBox::Detach() {
+  AbstractInlineTextBox::Detach();
   inline_text_box_ = nullptr;
 }
 
-scoped_refptr<AbstractInlineTextBox> AbstractInlineTextBox::NextInlineTextBox()
-    const {
+scoped_refptr<AbstractInlineTextBox>
+LegacyAbstractInlineTextBox::NextInlineTextBox() const {
   DCHECK(!inline_text_box_ ||
          !inline_text_box_->GetLineLayoutItem().NeedsLayout());
   if (!inline_text_box_)
     return nullptr;
 
-  return GetOrCreate(line_layout_item_,
+  return GetOrCreate(GetLineLayoutItem(),
                      inline_text_box_->NextForSameLayoutObject());
 }
 
-LayoutRect AbstractInlineTextBox::LocalBounds() const {
-  if (!inline_text_box_ || !line_layout_item_)
+LayoutRect LegacyAbstractInlineTextBox::LocalBounds() const {
+  if (!inline_text_box_ || !GetLineLayoutItem())
     return LayoutRect();
 
   return inline_text_box_->FrameRect();
 }
 
-unsigned AbstractInlineTextBox::Len() const {
+unsigned LegacyAbstractInlineTextBox::Len() const {
   if (!inline_text_box_)
     return 0;
 
   return inline_text_box_->Len();
 }
 
-AbstractInlineTextBox::Direction AbstractInlineTextBox::GetDirection() const {
-  if (!inline_text_box_ || !line_layout_item_)
+AbstractInlineTextBox::Direction LegacyAbstractInlineTextBox::GetDirection()
+    const {
+  if (!inline_text_box_ || !GetLineLayoutItem())
     return kLeftToRight;
 
-  if (line_layout_item_.Style()->IsHorizontalWritingMode()) {
+  if (GetLineLayoutItem().Style()->IsHorizontalWritingMode()) {
     return (inline_text_box_->Direction() == TextDirection::kRtl
                 ? kRightToLeft
                 : kLeftToRight);
@@ -127,12 +148,12 @@ AbstractInlineTextBox::Direction AbstractInlineTextBox::GetDirection() const {
 }
 
 Node* AbstractInlineTextBox::GetNode() const {
-  if (!line_layout_item_)
+  if (!GetLineLayoutItem())
     return nullptr;
-  return line_layout_item_.GetNode();
+  return GetLineLayoutItem().GetNode();
 }
 
-void AbstractInlineTextBox::CharacterWidths(Vector<float>& widths) const {
+void LegacyAbstractInlineTextBox::CharacterWidths(Vector<float>& widths) const {
   if (!inline_text_box_)
     return;
 
@@ -141,7 +162,7 @@ void AbstractInlineTextBox::CharacterWidths(Vector<float>& widths) const {
 
 void AbstractInlineTextBox::GetWordBoundaries(
     Vector<WordBoundaries>& words) const {
-  if (!inline_text_box_)
+  if (Len() == 0)
     return;
 
   String text = GetText();
@@ -161,13 +182,13 @@ void AbstractInlineTextBox::GetWordBoundaries(
   }
 }
 
-String AbstractInlineTextBox::GetText() const {
-  if (!inline_text_box_ || !line_layout_item_)
+String LegacyAbstractInlineTextBox::GetText() const {
+  if (!inline_text_box_ || !GetLineLayoutItem())
     return String();
 
   unsigned start = inline_text_box_->Start();
   unsigned len = inline_text_box_->Len();
-  if (Node* node = line_layout_item_.GetNode()) {
+  if (Node* node = GetLineLayoutItem().GetNode()) {
     if (node->IsTextNode()) {
       return PlainText(
           EphemeralRange(Position(node, start), Position(node, start + len)),
@@ -179,7 +200,8 @@ String AbstractInlineTextBox::GetText() const {
         TextIteratorBehavior::IgnoresStyleVisibilityBehavior());
   }
 
-  String result = line_layout_item_.GetText()
+  String result = GetLineLayoutItem()
+                      .GetText()
                       .Substring(start, len)
                       .SimplifyWhiteSpace(WTF::kDoNotStripWhiteSpace);
   if (inline_text_box_->NextForSameLayoutObject() &&
@@ -190,19 +212,20 @@ String AbstractInlineTextBox::GetText() const {
   return result;
 }
 
-bool AbstractInlineTextBox::IsFirst() const {
+bool LegacyAbstractInlineTextBox::IsFirst() const {
   DCHECK(!inline_text_box_ ||
          !inline_text_box_->GetLineLayoutItem().NeedsLayout());
   return !inline_text_box_ || !inline_text_box_->PrevForSameLayoutObject();
 }
 
-bool AbstractInlineTextBox::IsLast() const {
+bool LegacyAbstractInlineTextBox::IsLast() const {
   DCHECK(!inline_text_box_ ||
          !inline_text_box_->GetLineLayoutItem().NeedsLayout());
   return !inline_text_box_ || !inline_text_box_->NextForSameLayoutObject();
 }
 
-scoped_refptr<AbstractInlineTextBox> AbstractInlineTextBox::NextOnLine() const {
+scoped_refptr<AbstractInlineTextBox> LegacyAbstractInlineTextBox::NextOnLine()
+    const {
   DCHECK(!inline_text_box_ ||
          !inline_text_box_->GetLineLayoutItem().NeedsLayout());
   if (!inline_text_box_)
@@ -216,8 +239,8 @@ scoped_refptr<AbstractInlineTextBox> AbstractInlineTextBox::NextOnLine() const {
   return nullptr;
 }
 
-scoped_refptr<AbstractInlineTextBox> AbstractInlineTextBox::PreviousOnLine()
-    const {
+scoped_refptr<AbstractInlineTextBox>
+LegacyAbstractInlineTextBox::PreviousOnLine() const {
   DCHECK(!inline_text_box_ ||
          !inline_text_box_->GetLineLayoutItem().NeedsLayout());
   if (!inline_text_box_)

third_party/blink/renderer/core/layout/line/abstract_inline_text_box.h

@@ -47,19 +47,6 @@ class InlineTextBox;
 // get information about InlineTextBoxes without tight coupling.
 class CORE_EXPORT AbstractInlineTextBox
     : public RefCounted<AbstractInlineTextBox> {
- private:
-  AbstractInlineTextBox(LineLayoutText line_layout_item,
-                        InlineTextBox* inline_text_box)
-      : line_layout_item_(line_layout_item),
-        inline_text_box_(inline_text_box) {}
-
-  static scoped_refptr<AbstractInlineTextBox> GetOrCreate(LineLayoutText,
-                                                          InlineTextBox*);
-  static void WillDestroy(InlineTextBox*);
-
-  friend class LayoutText;
-  friend class InlineTextBox;
-
  public:
   struct WordBoundaries {
     DISALLOW_NEW_EXCEPT_PLACEMENT_NEW();
@@ -71,34 +58,71 @@ class CORE_EXPORT AbstractInlineTextBox
 
   enum Direction { kLeftToRight, kRightToLeft, kTopToBottom, kBottomToTop };
 
-  ~AbstractInlineTextBox();
+  virtual ~AbstractInlineTextBox();
 
   LineLayoutText GetLineLayoutItem() const { return line_layout_item_; }
 
-  scoped_refptr<AbstractInlineTextBox> NextInlineTextBox() const;
-  LayoutRect LocalBounds() const;
-  unsigned Len() const;
-  Direction GetDirection() const;
+  virtual void Detach();
+  virtual scoped_refptr<AbstractInlineTextBox> NextInlineTextBox() const = 0;
+  virtual LayoutRect LocalBounds() const = 0;
+  virtual unsigned Len() const = 0;
+  virtual Direction GetDirection() const = 0;
   Node* GetNode() const;
-  void CharacterWidths(Vector<float>&) const;
+  virtual void CharacterWidths(Vector<float>&) const = 0;
   void GetWordBoundaries(Vector<WordBoundaries>&) const;
-  String GetText() const;
-  bool IsFirst() const;
-  bool IsLast() const;
-  scoped_refptr<AbstractInlineTextBox> NextOnLine() const;
-  scoped_refptr<AbstractInlineTextBox> PreviousOnLine() const;
+  virtual String GetText() const = 0;
+  virtual bool IsFirst() const = 0;
+  virtual bool IsLast() const = 0;
+  virtual scoped_refptr<AbstractInlineTextBox> NextOnLine() const = 0;
+  virtual scoped_refptr<AbstractInlineTextBox> PreviousOnLine() const = 0;
 
- private:
-  void Detach();
+ protected:
+  explicit AbstractInlineTextBox(LineLayoutText line_layout_item);
 
+ private:
   // Weak ptrs; these are nulled when InlineTextBox::destroy() calls
   // AbstractInlineTextBox::willDestroy.
   LineLayoutText line_layout_item_;
+};
+
+// The implementation of |AbstractInlineTextBox| for legacy layout.
+// See also |NGAbstractInlineTextBox| for LayoutNG.
+class CORE_EXPORT LegacyAbstractInlineTextBox final
+    : public AbstractInlineTextBox {
+ private:
+  LegacyAbstractInlineTextBox(LineLayoutText line_layout_item,
+                              InlineTextBox* inline_text_box);
+
+  static scoped_refptr<AbstractInlineTextBox> GetOrCreate(LineLayoutText,
+                                                          InlineTextBox*);
+  static void WillDestroy(InlineTextBox*);
+
+  friend class LayoutText;
+  friend class InlineTextBox;
+
+ public:
+  ~LegacyAbstractInlineTextBox() final;
+
+ private:
+  // Implementations of AbstractInlineTextBox member functions.
+  void Detach() final;
+  scoped_refptr<AbstractInlineTextBox> NextInlineTextBox() const final;
+  LayoutRect LocalBounds() const final;
+  unsigned Len() const final;
+  Direction GetDirection() const final;
+  void CharacterWidths(Vector<float>&) const final;
+  String GetText() const final;
+  bool IsFirst() const final;
+  bool IsLast() const final;
+  scoped_refptr<AbstractInlineTextBox> NextOnLine() const final;
+  scoped_refptr<AbstractInlineTextBox> PreviousOnLine() const final;
+
   InlineTextBox* inline_text_box_;
 
   typedef HashMap<InlineTextBox*, scoped_refptr<AbstractInlineTextBox>>
-      InlineToAbstractInlineTextBoxHashMap;
-  static InlineToAbstractInlineTextBoxHashMap* g_abstract_inline_text_box_map_;
+      InlineToLegacyAbstractInlineTextBoxHashMap;
+  static InlineToLegacyAbstractInlineTextBoxHashMap*
+      g_abstract_inline_text_box_map_;
 };
 
 }  // namespace blink

third_party/blink/renderer/core/layout/line/inline_text_box.cc

@@ -58,7 +58,7 @@ typedef WTF::HashMap<const InlineTextBox*, LayoutRect> InlineTextBoxOverflowMap;
 static InlineTextBoxOverflowMap* g_text_boxes_with_overflow;
 
 void InlineTextBox::Destroy() {
-  AbstractInlineTextBox::WillDestroy(this);
+  LegacyAbstractInlineTextBox::WillDestroy(this);
 
   if (!KnownToHaveNoOverflow() && g_text_boxes_with_overflow)
     g_text_boxes_with_overflow->erase(this);

third_party/blink/renderer/core/layout/ng/inline/ng_abstract_inline_text_box.cc

+// Copyright 2018 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "third_party/blink/renderer/core/layout/ng/inline/ng_abstract_inline_text_box.h"
+
+#include "third_party/blink/renderer/core/dom/ax_object_cache.h"
+#include "third_party/blink/renderer/core/layout/ng/inline/ng_physical_line_box_fragment.h"
+#include "third_party/blink/renderer/core/layout/ng/inline/ng_physical_text_fragment.h"
+#include "third_party/blink/renderer/core/paint/ng/ng_paint_fragment.h"
+#include "third_party/blink/renderer/core/paint/ng/ng_paint_fragment_traversal.h"
+
+namespace blink {
+
+NGAbstractInlineTextBox::FragmentToNGAbstractInlineTextBoxHashMap*
+    NGAbstractInlineTextBox::g_abstract_inline_text_box_map_ = nullptr;
+
+scoped_refptr<AbstractInlineTextBox> NGAbstractInlineTextBox::GetOrCreate(
+    LineLayoutText line_layout_item,
+    const NGPaintFragment& fragment) {
+  DCHECK(fragment.GetLayoutObject()->IsText()) << fragment.GetLayoutObject();
+  if (!g_abstract_inline_text_box_map_) {
+    g_abstract_inline_text_box_map_ =
+        new FragmentToNGAbstractInlineTextBoxHashMap();
+  }
+  const auto it = g_abstract_inline_text_box_map_->find(&fragment);
+  if (it != g_abstract_inline_text_box_map_->end())
+    return it->value;
+  scoped_refptr<AbstractInlineTextBox> obj =
+      base::AdoptRef(new NGAbstractInlineTextBox(line_layout_item, fragment));
+  g_abstract_inline_text_box_map_->Set(&fragment, obj);
+  return obj;
+}
+
+void NGAbstractInlineTextBox::WillDestroy(NGPaintFragment* fragment) {
+  if (!g_abstract_inline_text_box_map_)
+    return;
+  const auto it = g_abstract_inline_text_box_map_->find(fragment);
+  if (it != g_abstract_inline_text_box_map_->end()) {
+    it->value->Detach();
+    g_abstract_inline_text_box_map_->erase(fragment);
+  }
+}
+
+NGAbstractInlineTextBox::NGAbstractInlineTextBox(
+    LineLayoutText line_layout_item,
+    const NGPaintFragment& fragment)
+    : AbstractInlineTextBox(line_layout_item), fragment_(&fragment) {
+  DCHECK(fragment_->PhysicalFragment().IsText()) << fragment_;
+}
+
+NGAbstractInlineTextBox::~NGAbstractInlineTextBox() {
+  DCHECK(!fragment_);
+}
+
+void NGAbstractInlineTextBox::Detach() {
+  if (Node* const node = GetNode()) {
+    if (AXObjectCache* cache = node->GetDocument().ExistingAXObjectCache())
+      cache->InlineTextBoxesUpdated(GetLineLayoutItem());
+  }
+  AbstractInlineTextBox::Detach();
+  fragment_ = nullptr;
+}
+
+bool NGAbstractInlineTextBox::HasSoftWrapToNextLine() const {
+  return ToNGPhysicalLineBoxFragment(
+             fragment_->ContainerLineBox()->PhysicalFragment())
+      .HasSoftWrapToNextLine();
+}
+
+const NGPhysicalTextFragment& NGAbstractInlineTextBox::PhysicalTextFragment()
+    const {
+  return ToNGPhysicalTextFragment(fragment_->PhysicalFragment());
+}
+
+bool NGAbstractInlineTextBox::NeedsLayout() const {
+  return fragment_->GetLayoutObject()->NeedsLayout();
+}
+
+bool NGAbstractInlineTextBox::NeedsTrailingSpace() const {
+  if (!HasSoftWrapToNextLine())
+    return false;
+  const NGPaintFragment* next_fragment = NextTextFragmentForSameLayoutObject();
+  if (!next_fragment)
+    return false;
+  return ToNGPhysicalTextFragment(next_fragment->PhysicalFragment())
+             .StartOffset() != PhysicalTextFragment().EndOffset();
+}
+
+const NGPaintFragment*
+NGAbstractInlineTextBox::NextTextFragmentForSameLayoutObject() const {
+  const auto fragments =
+      NGPaintFragment::InlineFragmentsFor(fragment_->GetLayoutObject());
+  const auto it =
+      std::find_if(fragments.begin(), fragments.end(),
+                   [&](const auto& sibling) { return fragment_ == sibling; });
+  DCHECK(it != fragments.end());
+  const auto next_it = std::next(it);
+  return next_it == fragments.end() ? nullptr : *next_it;
+}
+
+scoped_refptr<AbstractInlineTextBox>
+NGAbstractInlineTextBox::NextInlineTextBox() const {
+  if (!fragment_)
+    return nullptr;
+  DCHECK(!NeedsLayout());
+  const NGPaintFragment* next_fragment = NextTextFragmentForSameLayoutObject();
+  if (!next_fragment)
+    return nullptr;
+  return GetOrCreate(GetLineLayoutItem(), *next_fragment);
+}
+
+LayoutRect NGAbstractInlineTextBox::LocalBounds() const {
+  if (!fragment_ || !GetLineLayoutItem())
+    return LayoutRect();
+  return LayoutRect(fragment_->InlineOffsetToContainerBox().ToLayoutPoint(),
+                    fragment_->Size().ToLayoutSize());
+}
+
+unsigned NGAbstractInlineTextBox::Len() const {
+  if (!fragment_)
+    return 0;
+  if (NeedsTrailingSpace())
+    return PhysicalTextFragment().Length() + 1;
+  return PhysicalTextFragment().Length();
+}
+
+AbstractInlineTextBox::Direction NGAbstractInlineTextBox::GetDirection() const {
+  if (!fragment_ || !GetLineLayoutItem())
+    return kLeftToRight;
+  const TextDirection text_direction =
+      PhysicalTextFragment().ResolvedDirection();
+  if (GetLineLayoutItem().Style()->IsHorizontalWritingMode())
+    return IsLtr(text_direction) ? kLeftToRight : kRightToLeft;
+  return IsLtr(text_direction) ? kTopToBottom : kBottomToTop;
+}
+
+void NGAbstractInlineTextBox::CharacterWidths(Vector<float>& widths) const {
+  if (!fragment_)
+    return;
+  // TODO(layout-dev): We should implement |CharacterWidths()|.
+  widths.resize(Len());
+}
+
+String NGAbstractInlineTextBox::GetText() const {
+  if (!fragment_ || !GetLineLayoutItem())
+    return String();
+  // For compatibility with |InlineTextBox|, we should have a space character
+  // for soft line break.
+  // Following tests require this:
+  //  - accessibility/inline-text-change-style.html
+  //  - accessibility/inline-text-changes.html
+  //  - accessibility/inline-text-word-boundaries.html
+  if (NeedsTrailingSpace())
+    return PhysicalTextFragment().Text().ToString() + " ";
+  return PhysicalTextFragment().Text().ToString();
+}
+
+bool NGAbstractInlineTextBox::IsFirst() const {
+  if (!fragment_)
+    return true;
+  DCHECK(!NeedsLayout());
+  const auto fragments =
+      NGPaintFragment::InlineFragmentsFor(fragment_->GetLayoutObject());
+  return fragment_ == &fragments.front();
+}
+
+bool NGAbstractInlineTextBox::IsLast() const {
+  if (!fragment_)
+    return true;
+  DCHECK(!NeedsLayout());
+  const auto fragments =
+      NGPaintFragment::InlineFragmentsFor(fragment_->GetLayoutObject());
+  return fragment_ == &fragments.back();
+}
+
+scoped_refptr<AbstractInlineTextBox> NGAbstractInlineTextBox::NextOnLine()
+    const {
+  if (!fragment_)
+    return nullptr;
+  DCHECK(!NeedsLayout());
+  DCHECK(fragment_->ContainerLineBox());
+  NGPaintFragmentTraversal cursor(*fragment_->ContainerLineBox(), *fragment_);
+  for (cursor.MoveToNext(); !cursor.IsAtEnd(); cursor.MoveToNext()) {
+    if (cursor->GetLayoutObject()->IsText())
+      return GetOrCreate(GetLineLayoutItem(), *cursor);
+  }
+  return nullptr;
+}
+
+scoped_refptr<AbstractInlineTextBox> NGAbstractInlineTextBox::PreviousOnLine()
+    const {
+  if (!fragment_)
+    return nullptr;
+  DCHECK(!NeedsLayout());
+  DCHECK(fragment_->ContainerLineBox());
+  NGPaintFragmentTraversal cursor(*fragment_->ContainerLineBox(), *fragment_);
+  for (cursor.MoveToPrevious(); !cursor.IsAtEnd(); cursor.MoveToPrevious()) {
+    if (cursor->GetLayoutObject()->IsText())
+      return GetOrCreate(GetLineLayoutItem(), *cursor);
+  }
+  return nullptr;
+}
+
+}  // namespace blink

third_party/blink/renderer/core/layout/ng/inline/ng_abstract_inline_text_box.h

+// Copyright 2018 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef THIRD_PARTY_BLINK_RENDERER_CORE_LAYOUT_NG_INLINE_NG_ABSTRACT_INLINE_TEXT_BOX_H_
+#define THIRD_PARTY_BLINK_RENDERER_CORE_LAYOUT_NG_INLINE_NG_ABSTRACT_INLINE_TEXT_BOX_H_
+
+#include "third_party/blink/renderer/core/layout/line/abstract_inline_text_box.h"
+
+namespace blink {
+
+class NGPaintFragment;
+class NGPhysicalTextFragment;
+
+// The implementation of |AbstractInlineTextBox| for LayoutNG.
+// See also |LegacyAbstractInlineTextBox| for legacy layout.
+class CORE_EXPORT NGAbstractInlineTextBox final : public AbstractInlineTextBox {
+ private:
+  // Returns existing or newly created |NGAbstractInlineTextBox|.
+  // * |line_layout_item| is |LayoutText| associated to |fragment|. For first
+  // letter part, it is remaining part of |LayoutTextFragment|.
+  // * |fragment| should be attached to |NGPhysicalTextFragment|.
+  static scoped_refptr<AbstractInlineTextBox> GetOrCreate(
+      LineLayoutText line_layout_item,
+      const NGPaintFragment& fragment);
+  static void WillDestroy(NGPaintFragment*);
+
+  friend class LayoutText;
+  friend class NGPaintFragment;
+
+ public:
+  ~NGAbstractInlineTextBox() final;
+
+ private:
+  NGAbstractInlineTextBox(LineLayoutText line_layout_item,
+                          const NGPaintFragment& fragment);
+
+  bool HasSoftWrapToNextLine() const;
+  const NGPhysicalTextFragment& PhysicalTextFragment() const;
+  bool NeedsLayout() const;
+  bool NeedsTrailingSpace() const;
+  // Returns next fragment associated to |LayoutText|.
+  const NGPaintFragment* NextTextFragmentForSameLayoutObject() const;
+
+  // Implementations of AbstractInlineTextBox member functions.
+  void Detach() final;
+  scoped_refptr<AbstractInlineTextBox> NextInlineTextBox() const final;
+  LayoutRect LocalBounds() const final;
+  unsigned Len() const final;
+  Direction GetDirection() const final;
+  void CharacterWidths(Vector<float>&) const final;
+  String GetText() const final;
+  bool IsFirst() const final;
+  bool IsLast() const final;
+  scoped_refptr<AbstractInlineTextBox> NextOnLine() const final;
+  scoped_refptr<AbstractInlineTextBox> PreviousOnLine() const final;
+
+  const NGPaintFragment* fragment_;
+
+  using FragmentToNGAbstractInlineTextBoxHashMap =
+      HashMap<const NGPaintFragment*, scoped_refptr<AbstractInlineTextBox>>;
+  static FragmentToNGAbstractInlineTextBoxHashMap*
+      g_abstract_inline_text_box_map_;
+};
+
+}  // namespace blink
+
+#endif  // THIRD_PARTY_BLINK_RENDERER_CORE_LAYOUT_NG_INLINE_NG_ABSTRACT_INLINE_TEXT_BOX_H_

third_party/blink/renderer/core/layout/ng/list/layout_ng_list_marker.cc

@@ -4,6 +4,7 @@
 
 #include "third_party/blink/renderer/core/layout/ng/list/layout_ng_list_marker.h"
 
+#include "third_party/blink/renderer/core/layout/layout_text.h"
 #include "third_party/blink/renderer/core/layout/ng/list/layout_ng_list_item.h"
 
 namespace blink {
@@ -64,4 +65,8 @@ LayoutObject* LayoutNGListMarker::SymbolMarkerLayoutText() const {
   return ListItem()->SymbolMarkerLayoutText();
 }
 
+String LayoutNGListMarker::TextAlternative() const {
+  return ToLayoutText(FirstChild())->GetText();
+}
+
 }  // namespace blink

third_party/blink/renderer/core/layout/ng/list/layout_ng_list_marker.h

@@ -35,6 +35,9 @@ class CORE_EXPORT LayoutNGListMarker final
 
   LayoutObject* SymbolMarkerLayoutText() const;
 
+  // Marker text with suffix, e.g. "1. ", for use in accessibility.
+  String TextAlternative() const;
+
   const char* GetName() const override { return "LayoutNGListMarker"; }
 
  private:

third_party/blink/renderer/core/paint/ng/ng_paint_fragment.cc

@@ -13,6 +13,7 @@
 #include "third_party/blink/renderer/core/layout/layout_inline.h"
 #include "third_party/blink/renderer/core/layout/ng/geometry/ng_logical_rect.h"
 #include "third_party/blink/renderer/core/layout/ng/geometry/ng_physical_offset_rect.h"
+#include "third_party/blink/renderer/core/layout/ng/inline/ng_abstract_inline_text_box.h"
 #include "third_party/blink/renderer/core/layout/ng/inline/ng_caret_position.h"
 #include "third_party/blink/renderer/core/layout/ng/inline/ng_offset_mapping.h"
 #include "third_party/blink/renderer/core/layout/ng/inline/ng_physical_line_box_fragment.h"
@@ -154,6 +155,10 @@ NGPaintFragment::NGPaintFragment(
   DCHECK(physical_fragment_);
 }
 
+NGPaintFragment::~NGPaintFragment() {
+  NGAbstractInlineTextBox::WillDestroy(this);
+}
+
 std::unique_ptr<NGPaintFragment> NGPaintFragment::Create(
     scoped_refptr<const NGPhysicalFragment> fragment) {
   std::unique_ptr<NGPaintFragment> paint_fragment =

third_party/blink/renderer/core/paint/ng/ng_paint_fragment.h

@@ -5,6 +5,8 @@
 #ifndef THIRD_PARTY_BLINK_RENDERER_CORE_PAINT_NG_NG_PAINT_FRAGMENT_H_
 #define THIRD_PARTY_BLINK_RENDERER_CORE_PAINT_NG_NG_PAINT_FRAGMENT_H_
 
+#include <iterator>
+
 #include "third_party/blink/renderer/core/core_export.h"
 #include "third_party/blink/renderer/core/layout/ng/ng_physical_fragment.h"
 #include "third_party/blink/renderer/core/loader/resource/image_resource_observer.h"
@@ -36,6 +38,7 @@ class CORE_EXPORT NGPaintFragment : public DisplayItemClient,
                                     public ImageResourceObserver {
  public:
   NGPaintFragment(scoped_refptr<const NGPhysicalFragment>, NGPaintFragment*);
+  ~NGPaintFragment() override;
   static std::unique_ptr<NGPaintFragment> Create(
       scoped_refptr<const NGPhysicalFragment>);
 
@@ -148,7 +151,8 @@ class CORE_EXPORT NGPaintFragment : public DisplayItemClient,
 
     bool IsEmpty() const { return !first_; }
 
-    class iterator {
+    class iterator final
+        : public std::iterator<std::forward_iterator_tag, NGPaintFragment*> {
      public:
       explicit iterator(NGPaintFragment* first) : current_(first) {}
 

third_party/blink/renderer/modules/accessibility/ax_layout_object.cc

@@ -82,6 +82,8 @@
 #include "third_party/blink/renderer/core/layout/layout_text_control.h"
 #include "third_party/blink/renderer/core/layout/layout_text_fragment.h"
 #include "third_party/blink/renderer/core/layout/layout_view.h"
+#include "third_party/blink/renderer/core/layout/ng/inline/ng_inline_node.h"
+#include "third_party/blink/renderer/core/layout/ng/list/layout_ng_list_marker.h"
 #include "third_party/blink/renderer/core/loader/progress_tracker.h"
 #include "third_party/blink/renderer/core/page/page.h"
 #include "third_party/blink/renderer/core/paint/ng/ng_paint_fragment.h"
@@ -137,6 +139,10 @@ static inline bool IsInlineWithContinuation(LayoutObject* object) {
 
 static inline LayoutObject* FirstChildConsideringContinuation(
     LayoutObject* layout_object) {
+  if (layout_object->IsLayoutNGListMarker()) {
+    // We don't care tree structure of list marker.
+    return nullptr;
+  }
   LayoutObject* first_child = layout_object->SlowFirstChild();
 
   // CSS first-letter pseudo element is handled as continuation. Returning it
@@ -257,7 +263,7 @@ AccessibilityRole AXLayoutObject::NativeAccessibilityRoleIgnoringAria() const {
 
   if ((css_box && css_box->IsListItem()) || IsHTMLLIElement(node))
     return kListItemRole;
-  if (layout_object_->IsListMarker())
+  if (layout_object_->IsListMarkerIncludingNG())
     return kListMarkerRole;
   if (layout_object_->IsBR())
     return kLineBreakRole;
@@ -542,6 +548,15 @@ bool HasAriaAttribute(Element* element) {
   return false;
 }
 
+static bool HasLineBox(const LayoutBlockFlow& block_flow) {
+  if (!block_flow.IsLayoutNGMixin())
+    return block_flow.FirstLineBox();
+  if (block_flow.HasNGInlineNodeData())
+    return !block_flow.GetNGInlineNodeData()->items.IsEmpty();
+  // TODO(layout-dev): We should call this function after layout completion.
+  return false;
+}
+
 bool AXLayoutObject::ComputeAccessibilityIsIgnored(
     IgnoredReasons* ignored_reasons) const {
 #if DCHECK_IS_ON()
@@ -750,7 +765,7 @@ bool AXLayoutObject::ComputeAccessibilityIsIgnored(
     // to decide.
   }
 
-  if (IsWebArea() || layout_object_->IsListMarker())
+  if (IsWebArea() || layout_object_->IsListMarkerIncludingNG())
     return false;
 
   // Using the help text, title or accessibility description (so we
@@ -788,7 +803,7 @@ bool AXLayoutObject::ComputeAccessibilityIsIgnored(
       !CanSetFocusAttribute()) {
     // If the layout object has any plain text in it, that text will be
     // inside a LineBox, so the layout object will have a first LineBox.
-    bool has_any_text = !!ToLayoutBlockFlow(layout_object_)->FirstLineBox();
+    bool has_any_text = HasLineBox(ToLayoutBlockFlow(*layout_object_));
 
     // Always include interesting-looking objects.
     if (has_any_text || MouseButtonListener())
@@ -1245,7 +1260,7 @@ static bool ShouldUseLayoutNG(const LayoutObject& layout_object) {
 static AXObject* NextOnLineInternalNG(const AXObject& ax_object) {
   DCHECK(ax_object.GetLayoutObject());
   const LayoutObject& layout_object = *ax_object.GetLayoutObject();
-  DCHECK(!layout_object.IsListMarker()) << layout_object;
+  DCHECK(!layout_object.IsListMarkerIncludingNG()) << layout_object;
   DCHECK(ShouldUseLayoutNG(layout_object)) << layout_object;
   const auto fragments = NGPaintFragment::InlineFragmentsFor(&layout_object);
   if (fragments.IsEmpty() || fragments.IsInLayoutNGInlineFormattingContext())
@@ -1271,7 +1286,7 @@ AXObject* AXLayoutObject::NextOnLine() const {
     return nullptr;
 
   AXObject* result = nullptr;
-  if (GetLayoutObject()->IsListMarker()) {
+  if (GetLayoutObject()->IsListMarkerIncludingNG()) {
     AXObject* next_sibling = RawNextSibling();
     if (!next_sibling || !next_sibling->Children().size())
       return nullptr;
@@ -1318,7 +1333,7 @@ AXObject* AXLayoutObject::NextOnLine() const {
 static AXObject* PreviousOnLineInlineNG(const AXObject& ax_object) {
   DCHECK(ax_object.GetLayoutObject());
   const LayoutObject& layout_object = *ax_object.GetLayoutObject();
-  DCHECK(!layout_object.IsListMarker()) << layout_object;
+  DCHECK(!layout_object.IsListMarkerIncludingNG()) << layout_object;
   DCHECK(ShouldUseLayoutNG(layout_object)) << layout_object;
   const auto fragments = NGPaintFragment::InlineFragmentsFor(&layout_object);
   if (fragments.IsEmpty() || fragments.IsInLayoutNGInlineFormattingContext())
@@ -1477,6 +1492,10 @@ String AXLayoutObject::TextAlternative(bool recursive,
     } else if (layout_object_->IsListMarker() && !recursive) {
       text_alternative = ToLayoutListMarker(layout_object_)->TextAlternative();
       found_text_alternative = true;
+    } else if (layout_object_->IsLayoutNGListMarker() && !recursive) {
+      text_alternative =
+          ToLayoutNGListMarker(layout_object_)->TextAlternative();
+      found_text_alternative = true;
     }
 
     if (found_text_alternative) {