Adding upstream version 124.0.1.upstream/124.0.1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 712 insertions, 0 deletions

diff --git a/accessible/html/HTMLTableAccessible.cpp b/accessible/html/HTMLTableAccessible.cpp
new file mode 100644
index 0000000000..2c3dc6b82d
--- /dev/null
+++ b/accessible/html/HTMLTableAccessible.cpp
@@ -0,0 +1,712 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "HTMLTableAccessible.h"
+
+#include <stdint.h>
+
+#include "nsAccessibilityService.h"
+#include "AccAttributes.h"
+#include "ARIAMap.h"
+#include "CacheConstants.h"
+#include "LocalAccessible-inl.h"
+#include "nsTextEquivUtils.h"
+#include "Relation.h"
+#include "mozilla/a11y/Role.h"
+#include "States.h"
+
+#include "mozilla/a11y/TableAccessible.h"
+#include "mozilla/a11y/TableCellAccessible.h"
+#include "mozilla/Assertions.h"
+#include "mozilla/dom/Element.h"
+#include "mozilla/dom/NameSpaceConstants.h"
+#include "nsCaseTreatment.h"
+#include "nsColor.h"
+#include "nsCOMPtr.h"
+#include "nsCoreUtils.h"
+#include "nsDebug.h"
+#include "nsIHTMLCollection.h"
+#include "nsError.h"
+#include "nsGkAtoms.h"
+#include "nsLiteralString.h"
+#include "nsMargin.h"
+#include "nsQueryFrame.h"
+#include "nsSize.h"
+#include "nsStringFwd.h"
+#include "nsTableCellFrame.h"
+#include "nsTableWrapperFrame.h"
+
+using namespace mozilla;
+using namespace mozilla::dom;
+using namespace mozilla::a11y;
+
+////////////////////////////////////////////////////////////////////////////////
+// HTMLTableCellAccessible
+////////////////////////////////////////////////////////////////////////////////
+
+HTMLTableCellAccessible::HTMLTableCellAccessible(nsIContent* aContent,
+                                                 DocAccessible* aDoc)
+    : HyperTextAccessible(aContent, aDoc) {
+  mType = eHTMLTableCellType;
+  mGenericTypes |= eTableCell;
+}
+
+////////////////////////////////////////////////////////////////////////////////
+// HTMLTableCellAccessible: LocalAccessible implementation
+
+role HTMLTableCellAccessible::NativeRole() const {
+  // We implement this rather than using the markup maps because we only want
+  // this role to be returned if this is a valid cell. An invalid cell (e.g. if
+  // the table has role="none") won't use this class, so it will get a generic
+  // role, since the markup map doesn't specify a role.
+  if (mContent->IsMathMLElement(nsGkAtoms::mtd_)) {
+    return roles::MATHML_CELL;
+  }
+  return roles::CELL;
+}
+
+uint64_t HTMLTableCellAccessible::NativeState() const {
+  uint64_t state = HyperTextAccessible::NativeState();
+
+  nsIFrame* frame = mContent->GetPrimaryFrame();
+  NS_ASSERTION(frame, "No frame for valid cell accessible!");
+
+  if (frame && frame->IsSelected()) {
+    state |= states::SELECTED;
+  }
+
+  return state;
+}
+
+uint64_t HTMLTableCellAccessible::NativeInteractiveState() const {
+  return HyperTextAccessible::NativeInteractiveState() | states::SELECTABLE;
+}
+
+already_AddRefed<AccAttributes> HTMLTableCellAccessible::NativeAttributes() {
+  RefPtr<AccAttributes> attributes = HyperTextAccessible::NativeAttributes();
+
+  // We only need to expose table-cell-index to clients. If we're in the content
+  // process, we don't need this, so building a CachedTableAccessible is very
+  // wasteful. This will be exposed by RemoteAccessible in the parent process
+  // instead.
+  if (!IPCAccessibilityActive()) {
+    if (const TableCellAccessible* cell = AsTableCell()) {
+      TableAccessible* table = cell->Table();
+      const uint32_t row = cell->RowIdx();
+      const uint32_t col = cell->ColIdx();
+      const int32_t cellIdx = table->CellIndexAt(row, col);
+      if (cellIdx != -1) {
+        attributes->SetAttribute(nsGkAtoms::tableCellIndex, cellIdx);
+      }
+    }
+  }
+
+  // abbr attribute
+
+  // Pick up object attribute from abbr DOM element (a child of the cell) or
+  // from abbr DOM attribute.
+  nsString abbrText;
+  if (ChildCount() == 1) {
+    LocalAccessible* abbr = LocalFirstChild();
+    if (abbr->IsAbbreviation()) {
+      nsIContent* firstChildNode = abbr->GetContent()->GetFirstChild();
+      if (firstChildNode) {
+        nsTextEquivUtils::AppendTextEquivFromTextContent(firstChildNode,
+                                                         &abbrText);
+      }
+    }
+  }
+  if (abbrText.IsEmpty()) {
+    mContent->AsElement()->GetAttr(nsGkAtoms::abbr, abbrText);
+  }
+
+  if (!abbrText.IsEmpty()) {
+    attributes->SetAttribute(nsGkAtoms::abbr, std::move(abbrText));
+  }
+
+  // axis attribute
+  nsString axisText;
+  mContent->AsElement()->GetAttr(nsGkAtoms::axis, axisText);
+  if (!axisText.IsEmpty()) {
+    attributes->SetAttribute(nsGkAtoms::axis, std::move(axisText));
+  }
+
+  return attributes.forget();
+}
+
+void HTMLTableCellAccessible::DOMAttributeChanged(int32_t aNameSpaceID,
+                                                  nsAtom* aAttribute,
+                                                  int32_t aModType,
+                                                  const nsAttrValue* aOldValue,
+                                                  uint64_t aOldState) {
+  HyperTextAccessible::DOMAttributeChanged(aNameSpaceID, aAttribute, aModType,
+                                           aOldValue, aOldState);
+
+  if (aAttribute == nsGkAtoms::headers || aAttribute == nsGkAtoms::abbr ||
+      aAttribute == nsGkAtoms::scope) {
+    mDoc->FireDelayedEvent(nsIAccessibleEvent::EVENT_OBJECT_ATTRIBUTE_CHANGED,
+                           this);
+    if (HTMLTableAccessible* table = Table()) {
+      // Modifying these attributes can also modify our table's classification
+      // as either a layout or data table. Queue an update on the table itself
+      // to re-compute our "layout guess"
+      mDoc->QueueCacheUpdate(table, CacheDomain::Table);
+    }
+    mDoc->QueueCacheUpdate(this, CacheDomain::Table);
+  } else if (aAttribute == nsGkAtoms::rowspan ||
+             aAttribute == nsGkAtoms::colspan) {
+    if (HTMLTableAccessible* table = Table()) {
+      // Modifying these attributes can also modify our table's classification
+      // as either a layout or data table. Queue an update on the table itself
+      // to re-compute our "layout guess"
+      mDoc->QueueCacheUpdate(table, CacheDomain::Table);
+    }
+    mDoc->QueueCacheUpdate(this, CacheDomain::Table);
+  }
+}
+
+////////////////////////////////////////////////////////////////////////////////
+// HTMLTableCellAccessible implementation
+
+HTMLTableAccessible* HTMLTableCellAccessible::Table() const {
+  LocalAccessible* parent = const_cast<HTMLTableCellAccessible*>(this);
+  while ((parent = parent->LocalParent())) {
+    if (parent->IsHTMLTable()) {
+      return HTMLTableAccessible::GetFrom(parent);
+    }
+  }
+
+  return nullptr;
+}
+
+uint32_t HTMLTableCellAccessible::ColExtent() const {
+  nsTableCellFrame* cell = do_QueryFrame(GetFrame());
+  if (!cell) {
+    // This probably isn't a table according to the layout engine; e.g. it has
+    // display: block.
+    return 1;
+  }
+  nsTableFrame* table = cell->GetTableFrame();
+  MOZ_ASSERT(table);
+  return table->GetEffectiveColSpan(*cell);
+}
+
+uint32_t HTMLTableCellAccessible::RowExtent() const {
+  nsTableCellFrame* cell = do_QueryFrame(GetFrame());
+  if (!cell) {
+    // This probably isn't a table according to the layout engine; e.g. it has
+    // display: block.
+    return 1;
+  }
+  nsTableFrame* table = cell->GetTableFrame();
+  MOZ_ASSERT(table);
+  return table->GetEffectiveRowSpan(*cell);
+}
+
+////////////////////////////////////////////////////////////////////////////////
+// HTMLTableHeaderCellAccessible
+////////////////////////////////////////////////////////////////////////////////
+
+HTMLTableHeaderCellAccessible::HTMLTableHeaderCellAccessible(
+    nsIContent* aContent, DocAccessible* aDoc)
+    : HTMLTableCellAccessible(aContent, aDoc) {}
+
+////////////////////////////////////////////////////////////////////////////////
+// HTMLTableHeaderCellAccessible: LocalAccessible implementation
+
+role HTMLTableHeaderCellAccessible::NativeRole() const {
+  dom::Element* el = Elm();
+  if (!el) {
+    return roles::NOTHING;
+  }
+
+  // Check value of @scope attribute.
+  static mozilla::dom::Element::AttrValuesArray scopeValues[] = {
+      nsGkAtoms::col, nsGkAtoms::colgroup, nsGkAtoms::row, nsGkAtoms::rowgroup,
+      nullptr};
+  int32_t valueIdx = el->FindAttrValueIn(kNameSpaceID_None, nsGkAtoms::scope,
+                                         scopeValues, eCaseMatters);
+
+  switch (valueIdx) {
+    case 0:
+    case 1:
+      return roles::COLUMNHEADER;
+    case 2:
+    case 3:
+      return roles::ROWHEADER;
+  }
+
+  dom::Element* nextEl = el->GetNextElementSibling();
+  dom::Element* prevEl = el->GetPreviousElementSibling();
+  // If this is the only cell in its row, it's a column header.
+  if (!nextEl && !prevEl) {
+    return roles::COLUMNHEADER;
+  }
+  const bool nextIsHeader = nextEl && nsCoreUtils::IsHTMLTableHeader(nextEl);
+  const bool prevIsHeader = prevEl && nsCoreUtils::IsHTMLTableHeader(prevEl);
+  // If this has a header on both sides, it is a column header.
+  if (prevIsHeader && nextIsHeader) {
+    return roles::COLUMNHEADER;
+  }
+  // If this has a header on one side and only a single normal cell on the
+  // other, it's a column header.
+  if (nextIsHeader && prevEl && !prevEl->GetPreviousElementSibling()) {
+    return roles::COLUMNHEADER;
+  }
+  if (prevIsHeader && nextEl && !nextEl->GetNextElementSibling()) {
+    return roles::COLUMNHEADER;
+  }
+  // If this has a normal cell next to it, it 's a row header.
+  if ((nextEl && !nextIsHeader) || (prevEl && !prevIsHeader)) {
+    return roles::ROWHEADER;
+  }
+  // If this has a row span, it could be a row header.
+  if (RowExtent() > 1) {
+    // It isn't a row header if it has 1 or more consecutive headers next to it.
+    if (prevIsHeader &&
+        (!prevEl->GetPreviousElementSibling() ||
+         nsCoreUtils::IsHTMLTableHeader(prevEl->GetPreviousElementSibling()))) {
+      return roles::COLUMNHEADER;
+    }
+    if (nextIsHeader &&
+        (!nextEl->GetNextElementSibling() ||
+         nsCoreUtils::IsHTMLTableHeader(nextEl->GetNextElementSibling()))) {
+      return roles::COLUMNHEADER;
+    }
+    return roles::ROWHEADER;
+  }
+  // Otherwise, assume it's a column header.
+  return roles::COLUMNHEADER;
+}
+
+////////////////////////////////////////////////////////////////////////////////
+// HTMLTableRowAccessible
+////////////////////////////////////////////////////////////////////////////////
+
+// LocalAccessible protected
+ENameValueFlag HTMLTableRowAccessible::NativeName(nsString& aName) const {
+  // For table row accessibles, we only want to calculate the name from the
+  // sub tree if an ARIA role is present.
+  if (HasStrongARIARole()) {
+    return AccessibleWrap::NativeName(aName);
+  }
+
+  return eNameOK;
+}
+
+////////////////////////////////////////////////////////////////////////////////
+// HTMLTableAccessible
+////////////////////////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////////////////////////
+// HTMLTableAccessible: LocalAccessible
+
+bool HTMLTableAccessible::InsertChildAt(uint32_t aIndex,
+                                        LocalAccessible* aChild) {
+  // Move caption accessible so that it's the first child. Check for the first
+  // caption only, because nsAccessibilityService ensures we don't create
+  // accessibles for the other captions, since only the first is actually
+  // visible.
+  return HyperTextAccessible::InsertChildAt(
+      aChild->IsHTMLCaption() ? 0 : aIndex, aChild);
+}
+
+uint64_t HTMLTableAccessible::NativeState() const {
+  return LocalAccessible::NativeState() | states::READONLY;
+}
+
+ENameValueFlag HTMLTableAccessible::NativeName(nsString& aName) const {
+  ENameValueFlag nameFlag = LocalAccessible::NativeName(aName);
+  if (!aName.IsEmpty()) {
+    return nameFlag;
+  }
+
+  // Use table caption as a name.
+  LocalAccessible* caption = Caption();
+  if (caption) {
+    nsIContent* captionContent = caption->GetContent();
+    if (captionContent) {
+      nsTextEquivUtils::AppendTextEquivFromContent(this, captionContent,
+                                                   &aName);
+      if (!aName.IsEmpty()) {
+        return eNameOK;
+      }
+    }
+  }
+
+  // If no caption then use summary as a name.
+  mContent->AsElement()->GetAttr(nsGkAtoms::summary, aName);
+  return eNameOK;
+}
+
+void HTMLTableAccessible::DOMAttributeChanged(int32_t aNameSpaceID,
+                                              nsAtom* aAttribute,
+                                              int32_t aModType,
+                                              const nsAttrValue* aOldValue,
+                                              uint64_t aOldState) {
+  HyperTextAccessible::DOMAttributeChanged(aNameSpaceID, aAttribute, aModType,
+                                           aOldValue, aOldState);
+
+  if (aAttribute == nsGkAtoms::summary) {
+    nsAutoString name;
+    ARIAName(name);
+    if (name.IsEmpty()) {
+      if (!Caption()) {
+        // XXX: Should really be checking if caption provides a name.
+        mDoc->FireDelayedEvent(nsIAccessibleEvent::EVENT_NAME_CHANGE, this);
+      }
+    }
+
+    mDoc->FireDelayedEvent(nsIAccessibleEvent::EVENT_OBJECT_ATTRIBUTE_CHANGED,
+                           this);
+    mDoc->QueueCacheUpdate(this, CacheDomain::Table);
+  }
+}
+
+already_AddRefed<AccAttributes> HTMLTableAccessible::NativeAttributes() {
+  RefPtr<AccAttributes> attributes = AccessibleWrap::NativeAttributes();
+
+  if (mContent->IsMathMLElement(nsGkAtoms::mtable_)) {
+    GetAccService()->MarkupAttributes(this, attributes);
+  }
+
+  if (IsProbablyLayoutTable()) {
+    attributes->SetAttribute(nsGkAtoms::layout_guess, true);
+  }
+
+  return attributes.forget();
+}
+
+////////////////////////////////////////////////////////////////////////////////
+// HTMLTableAccessible: LocalAccessible
+
+Relation HTMLTableAccessible::RelationByType(RelationType aType) const {
+  Relation rel = AccessibleWrap::RelationByType(aType);
+  if (aType == RelationType::LABELLED_BY) {
+    rel.AppendTarget(Caption());
+  }
+
+  return rel;
+}
+
+////////////////////////////////////////////////////////////////////////////////
+// HTMLTableAccessible: Table
+
+LocalAccessible* HTMLTableAccessible::Caption() const {
+  LocalAccessible* child = mChildren.SafeElementAt(0, nullptr);
+  // Since this is an HTML table the caption needs to be a caption
+  // element with no ARIA role (except for a reduntant role='caption').
+  // If we did a full Role() calculation here we risk getting into an infinite
+  // loop where the parent role would depend on its name which would need to be
+  // calculated by retrieving the caption (bug 1420773.)
+  return child && child->NativeRole() == roles::CAPTION &&
+                 (!child->HasStrongARIARole() ||
+                  child->IsARIARole(nsGkAtoms::caption))
+             ? child
+             : nullptr;
+}
+
+uint32_t HTMLTableAccessible::ColCount() const {
+  nsTableWrapperFrame* tableFrame = GetTableWrapperFrame();
+  return tableFrame ? tableFrame->GetColCount() : 0;
+}
+
+uint32_t HTMLTableAccessible::RowCount() {
+  nsTableWrapperFrame* tableFrame = GetTableWrapperFrame();
+  return tableFrame ? tableFrame->GetRowCount() : 0;
+}
+
+bool HTMLTableAccessible::IsProbablyLayoutTable() {
+  // Implement a heuristic to determine if table is most likely used for layout.
+
+  // XXX do we want to look for rowspan or colspan, especialy that span all but
+  // a couple cells  at the beginning or end of a row/col, and especially when
+  // they occur at the edge of a table?
+
+  // XXX For now debugging descriptions are always on via SHOW_LAYOUT_HEURISTIC
+  // This will allow release trunk builds to be used by testers to refine
+  // the algorithm. Integrate it into Logging.
+  // Change to |#define SHOW_LAYOUT_HEURISTIC DEBUG| before final release
+#ifdef SHOW_LAYOUT_HEURISTIC
+#  define RETURN_LAYOUT_ANSWER(isLayout, heuristic)                         \
+    {                                                                       \
+      mLayoutHeuristic = isLayout                                           \
+                             ? nsLiteralString(u"layout table: " heuristic) \
+                             : nsLiteralString(u"data table: " heuristic);  \
+      return isLayout;                                                      \
+    }
+#else
+#  define RETURN_LAYOUT_ANSWER(isLayout, heuristic) \
+    { return isLayout; }
+#endif
+
+  MOZ_ASSERT(!IsDefunct(), "Table accessible should not be defunct");
+
+  // Need to see all elements while document is being edited.
+  if (Document()->State() & states::EDITABLE) {
+    RETURN_LAYOUT_ANSWER(false, "In editable document");
+  }
+
+  // Check to see if an ARIA role overrides the role from native markup,
+  // but for which we still expose table semantics (treegrid, for example).
+  if (HasARIARole()) {
+    RETURN_LAYOUT_ANSWER(false, "Has role attribute");
+  }
+
+  dom::Element* el = Elm();
+  if (el->IsMathMLElement(nsGkAtoms::mtable_)) {
+    RETURN_LAYOUT_ANSWER(false, "MathML matrix");
+  }
+
+  MOZ_ASSERT(el->IsHTMLElement(nsGkAtoms::table),
+             "Table should not be built by CSS display:table style");
+
+  // Check if datatable attribute has "0" value.
+  if (el->AttrValueIs(kNameSpaceID_None, nsGkAtoms::datatable, u"0"_ns,
+                      eCaseMatters)) {
+    RETURN_LAYOUT_ANSWER(true, "Has datatable = 0 attribute, it's for layout");
+  }
+
+  // Check for legitimate data table attributes.
+  if (el->Element::HasNonEmptyAttr(nsGkAtoms::summary)) {
+    RETURN_LAYOUT_ANSWER(false, "Has summary -- legitimate table structures");
+  }
+
+  // Check for legitimate data table elements.
+  LocalAccessible* caption = LocalFirstChild();
+  if (caption && caption->IsHTMLCaption() && caption->HasChildren()) {
+    RETURN_LAYOUT_ANSWER(false,
+                         "Not empty caption -- legitimate table structures");
+  }
+
+  for (nsIContent* childElm = el->GetFirstChild(); childElm;
+       childElm = childElm->GetNextSibling()) {
+    if (!childElm->IsHTMLElement()) continue;
+
+    if (childElm->IsAnyOfHTMLElements(nsGkAtoms::col, nsGkAtoms::colgroup,
+                                      nsGkAtoms::tfoot, nsGkAtoms::thead)) {
+      RETURN_LAYOUT_ANSWER(
+          false,
+          "Has col, colgroup, tfoot or thead -- legitimate table structures");
+    }
+
+    if (childElm->IsHTMLElement(nsGkAtoms::tbody)) {
+      for (nsIContent* rowElm = childElm->GetFirstChild(); rowElm;
+           rowElm = rowElm->GetNextSibling()) {
+        if (rowElm->IsHTMLElement(nsGkAtoms::tr)) {
+          if (LocalAccessible* row = Document()->GetAccessible(rowElm)) {
+            if (const nsRoleMapEntry* roleMapEntry = row->ARIARoleMap()) {
+              if (roleMapEntry->role != roles::ROW) {
+                RETURN_LAYOUT_ANSWER(true, "Repurposed tr with different role");
+              }
+            }
+          }
+
+          for (nsIContent* cellElm = rowElm->GetFirstChild(); cellElm;
+               cellElm = cellElm->GetNextSibling()) {
+            if (cellElm->IsHTMLElement()) {
+              if (cellElm->NodeInfo()->Equals(nsGkAtoms::th)) {
+                RETURN_LAYOUT_ANSWER(false,
+                                     "Has th -- legitimate table structures");
+              }
+
+              if (cellElm->AsElement()->HasAttr(nsGkAtoms::headers) ||
+                  cellElm->AsElement()->HasAttr(nsGkAtoms::scope) ||
+                  cellElm->AsElement()->HasAttr(nsGkAtoms::abbr)) {
+                RETURN_LAYOUT_ANSWER(false,
+                                     "Has headers, scope, or abbr attribute -- "
+                                     "legitimate table structures");
+              }
+
+              if (LocalAccessible* cell = Document()->GetAccessible(cellElm)) {
+                if (const nsRoleMapEntry* roleMapEntry = cell->ARIARoleMap()) {
+                  if (roleMapEntry->role != roles::CELL &&
+                      roleMapEntry->role != roles::COLUMNHEADER &&
+                      roleMapEntry->role != roles::ROWHEADER &&
+                      roleMapEntry->role != roles::GRID_CELL) {
+                    RETURN_LAYOUT_ANSWER(true,
+                                         "Repurposed cell with different role");
+                  }
+                }
+                if (cell->ChildCount() == 1 &&
+                    cell->LocalFirstChild()->IsAbbreviation()) {
+                  RETURN_LAYOUT_ANSWER(
+                      false, "has abbr -- legitimate table structures");
+                }
+              }
+            }
+          }
+        }
+      }
+    }
+  }
+
+  // If only 1 column or only 1 row, it's for layout.
+  auto colCount = ColCount();
+  if (colCount <= 1) {
+    RETURN_LAYOUT_ANSWER(true, "Has only 1 column");
+  }
+  auto rowCount = RowCount();
+  if (rowCount <= 1) {
+    RETURN_LAYOUT_ANSWER(true, "Has only 1 row");
+  }
+
+  // Check for many columns.
+  if (colCount >= 5) {
+    RETURN_LAYOUT_ANSWER(false, ">=5 columns");
+  }
+
+  // Now we know there are 2-4 columns and 2 or more rows. Check to see if
+  // there are visible borders on the cells.
+  // XXX currently, we just check the first cell -- do we really need to do
+  // more?
+  nsTableWrapperFrame* tableFrame = do_QueryFrame(el->GetPrimaryFrame());
+  if (!tableFrame) {
+    RETURN_LAYOUT_ANSWER(false, "table with no frame!");
+  }
+
+  nsIFrame* cellFrame = tableFrame->GetCellFrameAt(0, 0);
+  if (!cellFrame) {
+    RETURN_LAYOUT_ANSWER(false, "table's first cell has no frame!");
+  }
+
+  nsMargin border = cellFrame->StyleBorder()->GetComputedBorder();
+  if (border.top || border.bottom || border.left || border.right) {
+    RETURN_LAYOUT_ANSWER(false, "Has nonzero border-width on table cell");
+  }
+
+  // Check for nested tables.
+  nsCOMPtr<nsIHTMLCollection> nestedTables =
+      el->GetElementsByTagName(u"table"_ns);
+  if (nestedTables->Length() > 0) {
+    RETURN_LAYOUT_ANSWER(true, "Has a nested table within it");
+  }
+
+  // Rules for non-bordered tables with 2-4 columns and 2+ rows from here on
+  // forward.
+
+  // Check for styled background color across rows (alternating background
+  // color is a common feature for data tables).
+  auto childCount = ChildCount();
+  nscolor rowColor = 0;
+  nscolor prevRowColor;
+  for (auto childIdx = 0U; childIdx < childCount; childIdx++) {
+    LocalAccessible* child = LocalChildAt(childIdx);
+    if (child->IsHTMLTableRow()) {
+      prevRowColor = rowColor;
+      nsIFrame* rowFrame = child->GetFrame();
+      MOZ_ASSERT(rowFrame, "Table hierarchy got screwed up");
+      if (!rowFrame) {
+        RETURN_LAYOUT_ANSWER(false, "Unexpected table hierarchy");
+      }
+
+      rowColor = rowFrame->StyleBackground()->BackgroundColor(rowFrame);
+
+      if (childIdx > 0 && prevRowColor != rowColor) {
+        RETURN_LAYOUT_ANSWER(false,
+                             "2 styles of row background color, non-bordered");
+      }
+    }
+  }
+
+  // Check for many rows.
+  const uint32_t kMaxLayoutRows = 20;
+  if (rowCount > kMaxLayoutRows) {  // A ton of rows, this is probably for data
+    RETURN_LAYOUT_ANSWER(false, ">= kMaxLayoutRows (20) and non-bordered");
+  }
+
+  // Check for very wide table.
+  nsIFrame* documentFrame = Document()->GetFrame();
+  nsSize documentSize = documentFrame->GetSize();
+  if (documentSize.width > 0) {
+    nsSize tableSize = GetFrame()->GetSize();
+    int32_t percentageOfDocWidth = (100 * tableSize.width) / documentSize.width;
+    if (percentageOfDocWidth > 95) {
+      // 3-4 columns, no borders, not a lot of rows, and 95% of the doc's width
+      // Probably for layout
+      RETURN_LAYOUT_ANSWER(
+          true, "<= 4 columns, table width is 95% of document width");
+    }
+  }
+
+  // Two column rules.
+  if (rowCount * colCount <= 10) {
+    RETURN_LAYOUT_ANSWER(true, "2-4 columns, 10 cells or less, non-bordered");
+  }
+
+  static const nsLiteralString tags[] = {u"embed"_ns, u"object"_ns,
+                                         u"iframe"_ns};
+  for (const auto& tag : tags) {
+    nsCOMPtr<nsIHTMLCollection> descendants = el->GetElementsByTagName(tag);
+    if (descendants->Length() > 0) {
+      RETURN_LAYOUT_ANSWER(true,
+                           "Has no borders, and has iframe, object or embed, "
+                           "typical of advertisements");
+    }
+  }
+
+  RETURN_LAYOUT_ANSWER(false,
+                       "No layout factor strong enough, so will guess data");
+}
+
+////////////////////////////////////////////////////////////////////////////////
+// HTMLTableAccessible: protected implementation
+
+void HTMLTableAccessible::Description(nsString& aDescription) const {
+  // Helpful for debugging layout vs. data tables
+  aDescription.Truncate();
+  LocalAccessible::Description(aDescription);
+  if (!aDescription.IsEmpty()) {
+    return;
+  }
+
+  // Use summary as description if it weren't used as a name.
+  // XXX: get rid code duplication with NameInternal().
+  LocalAccessible* caption = Caption();
+  if (caption) {
+    nsIContent* captionContent = caption->GetContent();
+    if (captionContent) {
+      nsAutoString captionText;
+      nsTextEquivUtils::AppendTextEquivFromContent(this, captionContent,
+                                                   &captionText);
+
+      if (!captionText.IsEmpty()) {  // summary isn't used as a name.
+        mContent->AsElement()->GetAttr(nsGkAtoms::summary, aDescription);
+      }
+    }
+  }
+
+#ifdef SHOW_LAYOUT_HEURISTIC
+  if (aDescription.IsEmpty()) {
+    bool isProbablyForLayout = IsProbablyLayoutTable();
+    aDescription = mLayoutHeuristic;
+  }
+  printf("\nTABLE: %s\n", NS_ConvertUTF16toUTF8(mLayoutHeuristic).get());
+#endif
+}
+
+nsTableWrapperFrame* HTMLTableAccessible::GetTableWrapperFrame() const {
+  nsTableWrapperFrame* tableFrame = do_QueryFrame(mContent->GetPrimaryFrame());
+  if (tableFrame && tableFrame->PrincipalChildList().FirstChild()) {
+    return tableFrame;
+  }
+
+  return nullptr;
+}
+
+////////////////////////////////////////////////////////////////////////////////
+// HTMLCaptionAccessible
+////////////////////////////////////////////////////////////////////////////////
+
+Relation HTMLCaptionAccessible::RelationByType(RelationType aType) const {
+  Relation rel = HyperTextAccessible::RelationByType(aType);
+  if (aType == RelationType::LABEL_FOR) {
+    rel.AppendTarget(LocalParent());
+  }
+
+  return rel;
+}
+
+role HTMLCaptionAccessible::NativeRole() const { return roles::CAPTION; }