Introduce internal accessibility role for the <math> tag

Typical use case for ARIA role="math" [1] is to provide HTML markup with
math content in a textual representation. Chrome currently treats nodes
with such a role as a leaf, with presentational children and supporting
name from contents. This is however the contrary to what is desired for
MathML's <math> element (at least on ATK and AX API), for which the
MathML descendants are expected to be exposed in the accessibility tree
and for which spoken text is determined by the AT from these
descendants.

The MathML AAM spec currently does not specify how to map the <math>
tag [2] but the HTML AAM spec says it should use role="math"
with WAI-ARIA mapping [3]. This CL introduces an internal mathMLMath
role that is used for the default role of the <math> tag and is
following the same mapping. It enables the exposure difference
mentioned above while still preserving backward compatibility for
content using role="math". While MathMLCore is disabled, the <math>
tag remains mapped to role="math" by default.

AX-Relnotes: n/a.

[1] https://w3c.github.io/aria/#math
[2] w3c/mathml-aam#9
[3] https://w3c.github.io/html-aam/#html-element-role-mappings

Bug: 6606, 1038895, 1051115
Change-Id: I47dedcb53e8496e40142dc5d2d53c1f2ebe6b918
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3222742
Commit-Queue: Frédéric Wang <[email protected]>
Reviewed-by: Tom Sepez <[email protected]>
Reviewed-by: Nektarios Paisios <[email protected]>
Cr-Commit-Position: refs/heads/main@{#933395}

content/browser/accessibility/browser_accessibility_android.cc

@@ -1461,6 +1461,7 @@ std::u16string BrowserAccessibilityAndroid::GetRoleDescription() const {
  message_id = IDS_AX_ROLE_MARQUEE;
  break;
  case ax::mojom::Role::kMath:
+ case ax::mojom::Role::kMathMLMath:
  message_id = IDS_AX_ROLE_MATH;
  break;
  case ax::mojom::Role::kMenu:

content/browser/accessibility/browser_accessibility_cocoa.mm

@@ -2081,6 +2081,7 @@ - (NSString*)roleDescription {
  return base::SysUTF16ToNSString(
  content_client->GetLocalizedString(IDS_AX_ROLE_MARK));
  case ax::mojom::Role::kMath:
+ case ax::mojom::Role::kMathMLMath:
  return base::SysUTF16ToNSString(
  content_client->GetLocalizedString(IDS_AX_ROLE_MATH));
  case ax::mojom::Role::kNavigation:

content/browser/accessibility/browser_accessibility_com_win.cc

@@ -1200,7 +1200,8 @@ IFACEMETHODIMP BrowserAccessibilityComWin::get_innerHTML(BSTR* innerHTML) {
  AddAccessibilityModeFlags(kScreenReaderAndHTMLAccessibilityModes);
  if (!owner())
  return E_FAIL;
- if (owner()->GetRole() != ax::mojom::Role::kMath)
+ if (owner()->GetRole() != ax::mojom::Role::kMath &&
+ owner()->GetRole() != ax::mojom::Role::kMathMLMath)
  return E_NOTIMPL;
 
  std::u16string inner_html =

content/test/data/accessibility/html/math-expected-android.txt

@@ -1,8 +1,8 @@
 android.webkit.WebView focusable focused scrollable
 ++android.view.View
-++++android.view.View role_description='math' name='%F0%9D%90%B4 2 + %F0%9D%90%B5 2'
+++++android.view.View role_description='math'
 ++++++android.widget.TextView name='%F0%9D%90%B4'
 ++++++android.widget.TextView name='2'
 ++++++android.widget.TextView name='+'
 ++++++android.widget.TextView name='%F0%9D%90%B5'
-++++++android.widget.TextView name='2'
+++++++android.widget.TextView name='2'

content/test/data/accessibility/html/math-expected-auralinux.txt

@@ -1,6 +1,6 @@
 [document web]
 ++[section]
-++++[math] name='%F0%9D%90%B4 2 + %F0%9D%90%B5 2'
+++++[math]
 ++++++[section]
 ++++++++[static] name='%F0%9D%90%B4'
 ++++++[section]
@@ -10,4 +10,4 @@
 ++++++[section]
 ++++++++[static] name='%F0%9D%90%B5'
 ++++++[section]
-++++++++[static] name='2'
+++++++++[static] name='2'

content/test/data/accessibility/html/math-expected-mac.txt

@@ -1,6 +1,6 @@
 AXWebArea AXRoleDescription='HTML content'
 ++AXGroup AXRoleDescription='group'
-++++AXGroup AXSubrole=AXDocumentMath AXRoleDescription='math' AXTitle='%F0%9D%90%B4 2 + %F0%9D%90%B5 2'
+++++AXGroup AXSubrole=AXDocumentMath AXRoleDescription='math'
 ++++++AXGroup AXRoleDescription='group'
 ++++++++AXStaticText AXRoleDescription='text' AXValue='%F0%9D%90%B4'
 ++++++AXGroup AXRoleDescription='group'
@@ -10,4 +10,4 @@ AXWebArea AXRoleDescription='HTML content'
 ++++++AXGroup AXRoleDescription='group'
 ++++++++AXStaticText AXRoleDescription='text' AXValue='%F0%9D%90%B5'
 ++++++AXGroup AXRoleDescription='group'
-++++++++AXStaticText AXRoleDescription='text' AXValue='2'
+++++++++AXStaticText AXRoleDescription='text' AXValue='2'

content/test/data/accessibility/html/math-expected-uia-win.txt

@@ -1,6 +1,6 @@
 Document
 ++Group IsControlElement=false
-++++Group Name='%F0%9D%90%B4 2 + %F0%9D%90%B5 2'
+++++Group IsControlElement=false
 ++++++Group IsControlElement=false
 ++++++++Text Name='%F0%9D%90%B4'
 ++++++Group IsControlElement=false
@@ -10,4 +10,4 @@ Document
 ++++++Group IsControlElement=false
 ++++++++Text Name='%F0%9D%90%B5'
 ++++++Group IsControlElement=false
-++++++++Text Name='2'
+++++++++Text Name='2'

content/test/data/accessibility/html/math-expected-win.txt

@@ -1,6 +1,6 @@
 ROLE_SYSTEM_DOCUMENT READONLY FOCUSABLE
 ++IA2_ROLE_SECTION
-++++ROLE_SYSTEM_EQUATION name='%F0%9D%90%B4 2 + %F0%9D%90%B5 2' inner_html='<newline> <mrow><newline> <msup><mi>%F0%9D%90%B4</mi><mn>2</mn></msup><newline> <mo>+</mo><newline> <msup><mi>%F0%9D%90%B5</mi><mn>2</mn></msup><newline> </mrow><newline> '
+++++ROLE_SYSTEM_EQUATION inner_html='<newline> <mrow><newline> <msup><mi>%F0%9D%90%B4</mi><mn>2</mn></msup><newline> <mo>+</mo><newline> <msup><mi>%F0%9D%90%B5</mi><mn>2</mn></msup><newline> </mrow><newline> '
 ++++++IA2_ROLE_SECTION
 ++++++++ROLE_SYSTEM_STATICTEXT name='%F0%9D%90%B4'
 ++++++IA2_ROLE_SECTION
@@ -10,4 +10,4 @@ ROLE_SYSTEM_DOCUMENT READONLY FOCUSABLE
 ++++++IA2_ROLE_SECTION
 ++++++++ROLE_SYSTEM_STATICTEXT name='%F0%9D%90%B5'
 ++++++IA2_ROLE_SECTION
-++++++++ROLE_SYSTEM_STATICTEXT name='2'
+++++++++ROLE_SYSTEM_STATICTEXT name='2'

content/test/data/accessibility/html/math-name-from-contents-expected-blink.txt

@@ -1,7 +1,7 @@
 rootWebArea
 ++genericContainer ignored
 ++++genericContainer ignored
-++++++radioButton name='Both%C2%A01 + 4%C2%A0and%C2%A02 + 3' checkedState=false
+++++++radioButton name='Both%C2%A01 + 4%C2%A0and%C2%A0' checkedState=false
 ++++++++staticText name='Both%C2%A0'
 ++++++++++inlineTextBox name='Both%C2%A0'
 ++++++++math name='1 + 4'
@@ -16,7 +16,7 @@ rootWebArea
 ++++++++++++++inlineTextBox name='4'
 ++++++++staticText name='%C2%A0and%C2%A0'
 ++++++++++inlineTextBox name='%C2%A0and%C2%A0'
-++++++++math name='2 + 3'
+++++++++mathMLMath
 ++++++++++genericContainer
 ++++++++++++staticText name='2'
 ++++++++++++++inlineTextBox name='2'
@@ -25,4 +25,4 @@ rootWebArea
 ++++++++++++++inlineTextBox name='+'
 ++++++++++genericContainer
 ++++++++++++staticText name='3'
-++++++++++++++inlineTextBox name='3'
+++++++++++++++inlineTextBox name='3'

content/test/data/accessibility/html/math-name-from-contents.html

@@ -5,7 +5,7 @@
 
  <div role="radio" tabindex=0>
  <span>Both&nbsp;</span>
- <math><mn>1</mn><mo>+</mo><mn>4</mn></math>
+ <math role="math"><mn>1</mn><mo>+</mo><mn>4</mn></math>
  <span>&nbsp;and&nbsp;</span>
  <math><mn>2</mn><mo>+</mo><mn>3</mn></math>
  </div>

content/test/data/accessibility/html/svg-and-math-elements-expected-blink.txt

@@ -6,7 +6,7 @@ rootWebArea htmlTag='#document'
 ++++++++genericContainer className='html-namespace' htmlTag='svg' name='created'
 ++++++++genericContainer className='custom-namespace' htmlTag='svg' name='created'
 ++++++genericContainer className='math-container' htmlTag='div'
-++++++++math htmlTag='math' name='original'
+++++++++mathMLMath htmlTag='math' name='original'
 ++++++++genericContainer className='html-namespace' htmlTag='math' name='created'
 ++++++++genericContainer className='custom-namespace' htmlTag='math' name='created'
 ++++++staticText name='Done'

content/test/data/accessibility/mathml/mspace-expected-blink.txt

@@ -4,4 +4,4 @@ rootWebArea
 ++++++paragraph
 ++++++++staticText name='This test passes if the 'math' node in the accessibility tree is empty:'
 ++++++++++inlineTextBox name='This test passes if the 'math' node in the accessibility tree is empty:'
-++++++math
+++++++mathMLMath

extensions/common/api/automation.idl

@@ -267,6 +267,7 @@
  mark,
  marquee,
  math,
+ mathMLMath,
  menu,
  menuBar,
  menuItem,

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

@@ -126,6 +126,7 @@
 #include "third_party/blink/renderer/modules/accessibility/ax_relation_cache.h"
 #include "third_party/blink/renderer/platform/graphics/image_data_buffer.h"
 #include "third_party/blink/renderer/platform/keyboard_codes.h"
+#include "third_party/blink/renderer/platform/runtime_enabled_features.h"
 #include "third_party/blink/renderer/platform/text/platform_locale.h"
 #include "third_party/blink/renderer/platform/text/text_direction.h"
 #include "third_party/blink/renderer/platform/weborigin/kurl.h"
@@ -557,6 +558,7 @@ AXObjectInclusion AXNodeObject::ShouldIncludeBasedOnSemantics(
  ax::mojom::blink::Role::kMain,
  ax::mojom::blink::Role::kMark,
  ax::mojom::blink::Role::kMath,
+ ax::mojom::blink::Role::kMathMLMath,
  ax::mojom::blink::Role::kMeter,
  ax::mojom::blink::Role::kNavigation,
  ax::mojom::blink::Role::kPluginObject,
@@ -1066,8 +1068,11 @@ ax::mojom::blink::Role AXNodeObject::NativeRoleIgnoringAria() const {
 
  // Mapping of MathML elements. See https://w3c.github.io/mathml-aam/
  if (auto* element = DynamicTo<MathMLElement>(GetNode())) {
- if (element->HasTagName(mathml_names::kMathTag))
- return ax::mojom::blink::Role::kMath;
+ if (element->HasTagName(mathml_names::kMathTag)) {
+ return RuntimeEnabledFeatures::MathMLCoreEnabled()
+ ? ax::mojom::blink::Role::kMathMLMath
+ : ax::mojom::blink::Role::kMath;
+ }
  // TODO(crbug.com/6606): Map more MathML elements.
  if (element->HasTagName(mathml_names::kMspaceTag))
  return ax::mojom::blink::Role::kNone;

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

@@ -1527,7 +1527,8 @@ void AXObject::SerializeHTMLAttributes(ui::AXNodeData* node_data) {
 // TODO(nektar): Turn off kHTMLAccessibilityMode for automation and Mac
 // and remove ifdef.
 #if defined(OS_WIN) || defined(OS_CHROMEOS)
- if (node_data->role == ax::mojom::blink::Role::kMath &&
+ if ((node_data->role == ax::mojom::blink::Role::kMath ||
+ node_data->role == ax::mojom::blink::Role::kMathMLMath) &&
  element->innerHTML().length()) {
  TruncateAndAddStringAttribute(node_data,
  ax::mojom::blink::StringAttribute::kInnerHtml,
@@ -5639,6 +5640,7 @@ bool AXObject::SupportsNameFromContents(bool recursive) const {
  case ax::mojom::blink::Role::kLog:
  case ax::mojom::blink::Role::kMain:
  case ax::mojom::blink::Role::kMarquee:
+ case ax::mojom::blink::Role::kMathMLMath:
  case ax::mojom::blink::Role::kMenuListPopup:
  case ax::mojom::blink::Role::kMenu:
  case ax::mojom::blink::Role::kMenuBar:

third_party/blink/web_tests/accessibility/element-role-mapping-normal-expected.txt

@@ -14,6 +14,12 @@ x
 a
 /
 b
+
+𝑥
++
+𝑎
+/
+𝑏
 Most important heading here
 Google Chrome
 
@@ -99,6 +105,24 @@ AXRole: AXGenericContainer
  AXRole: AXGenericContainer
  AXRole: AXStaticText "b"
  AXRole: AXInlineTextBox "b"
+ AXRole: AXMathMLMath
+ AXRole: AXGenericContainer
+ AXRole: AXGenericContainer
+ AXRole: AXStaticText "𝑥"
+ AXRole: AXInlineTextBox "𝑥"
+ AXRole: AXGenericContainer
+ AXRole: AXStaticText "+"
+ AXRole: AXInlineTextBox "+"
+ AXRole: AXGenericContainer
+ AXRole: AXGenericContainer
+ AXRole: AXStaticText "𝑎"
+ AXRole: AXInlineTextBox "𝑎"
+ AXRole: AXGenericContainer
+ AXRole: AXStaticText "/"
+ AXRole: AXInlineTextBox "/"
+ AXRole: AXGenericContainer
+ AXRole: AXStaticText "𝑏"
+ AXRole: AXInlineTextBox "𝑏"
  AXRole: AXMain
  AXRole: AXArticle
  AXRole: AXHeaderAsNonLandmark

third_party/blink/web_tests/accessibility/element-role-mapping-normal.html

@@ -17,7 +17,7 @@ <h1>Heading</h1>
  <dt>Milk</dt>
  <dd>- white cold drink</dd>
 </dl>
-<math xmlns="http://www.w3.org/1998/Math/MathML">
+<math role="math" xmlns="http://www.w3.org/1998/Math/MathML">
  <mrow>
  <mi> x </mi>
  <mo> + </mo>
@@ -28,6 +28,17 @@ <h1>Heading</h1>
  </mrow>
  </mrow>
 </math>
+<math xmlns="http://www.w3.org/1998/Math/MathML">
+ <mrow>
+ <mi>x</mi>
+ <mo>+</mo>
+ <mrow>
+ <mi>a</mi>
+ <mo>/</mo>
+ <mi>b</mi>
+ </mrow>
+ </mrow>
+</math>
 <main>
  <article>
  <header>

third_party/closure_compiler/externs/automation.js

@@ -266,6 +266,7 @@ chrome.automation.RoleType = {
  MARK: 'mark',
  MARQUEE: 'marquee',
  MATH: 'math',
+ MATH_MLMATH: 'mathMLMath',
  MENU: 'menu',
  MENU_BAR: 'menuBar',
  MENU_ITEM: 'menuItem',

ui/accessibility/ax_enum_util.cc

@@ -382,6 +382,8 @@ const char* ToString(ax::mojom::Role role) {
  return "marquee";
  case ax::mojom::Role::kMath:
  return "math";
+ case ax::mojom::Role::kMathMLMath:
+ return "mathMLMath";
  case ax::mojom::Role::kMenu:
  return "menu";
  case ax::mojom::Role::kMenuBar:

ui/accessibility/ax_enums.mojom

@@ -106,8 +106,8 @@ enum Event {
 // Web: this attribute is only used in web content.
 //
 // Native: this attribute is only used in native UI.
-// Next version: 2
-// Next value: 187
+// Next version: 3
+// Next value: 188
 [Extensible, Stable, Uuid="d258eb73-e0cc-490c-b881-80ee11d3fec2"]
 enum Role {
  // Used for role="none"/"presentation" -- ignored in platform tree.
@@ -246,6 +246,7 @@ enum Role {
  kMark = 119,
  kMarquee = 120,
  kMath = 121,
+ [MinVersion=2] kMathMLMath = 187,
  kMenu = 122,
  kMenuBar = 123,
  kMenuItem = 124,

ui/accessibility/ax_node.cc

@@ -1707,7 +1707,9 @@ bool AXNode::IsLeaf() const {
  return true;
  case ax::mojom::Role::kCheckBox:
  case ax::mojom::Role::kListBoxOption:
- case ax::mojom::Role::kMath: // role="math" is flat, unlike <math>.
+ // role="math" is flat. But always return false for kMathMLMath since the
+ // children of a <math> tag should be exposed to make MathML accessible.
+ case ax::mojom::Role::kMath:
  case ax::mojom::Role::kMenuListOption:
  case ax::mojom::Role::kMenuItem:
  case ax::mojom::Role::kMenuItemCheckBox:

ui/accessibility/ax_role_properties.cc

@@ -39,6 +39,8 @@ bool HasPresentationalChildren(const ax::mojom::Role role) {
  case ax::mojom::Role::kButton:
  case ax::mojom::Role::kCheckBox:
  case ax::mojom::Role::kMath:
+ // Return false for kMathMLMath, since the children of a <math> tag should
+ // be exposed to make MathML accessible.
  case ax::mojom::Role::kMenuItemCheckBox:
  case ax::mojom::Role::kMenuItemRadio:
  case ax::mojom::Role::kMenuListOption:
@@ -570,6 +572,7 @@ bool IsSection(const ax::mojom::Role role) {
  case ax::mojom::Role::kLog:
  case ax::mojom::Role::kMarquee:
  case ax::mojom::Role::kMath:
+ case ax::mojom::Role::kMathMLMath:
  case ax::mojom::Role::kNote:
  case ax::mojom::Role::kProgressIndicator: // Subclass of kStatus.
  case ax::mojom::Role::kRow: // Subclass of kGroup.

ui/accessibility/platform/ax_platform_node_auralinux.cc

@@ -2851,6 +2851,7 @@ AtkRole AXPlatformNodeAuraLinux::GetAtkRole() const {
  case ax::mojom::Role::kMark:
  return kStaticRole;
  case ax::mojom::Role::kMath:
+ case ax::mojom::Role::kMathMLMath:
  return ATK_ROLE_MATH;
  case ax::mojom::Role::kMarquee:
  return ATK_ROLE_MARQUEE;

ui/accessibility/platform/ax_platform_node_cocoa.mm

@@ -166,6 +166,7 @@ RoleMap BuildRoleMap() {
  {ax::mojom::Role::kMark, NSAccessibilityGroupRole},
  {ax::mojom::Role::kMarquee, NSAccessibilityGroupRole},
  {ax::mojom::Role::kMath, NSAccessibilityGroupRole},
+ {ax::mojom::Role::kMathMLMath, NSAccessibilityGroupRole},
  {ax::mojom::Role::kMenu, NSAccessibilityMenuRole},
  {ax::mojom::Role::kMenuBar, NSAccessibilityMenuBarRole},
  {ax::mojom::Role::kMenuItem, NSAccessibilityMenuItemRole},
@@ -266,6 +267,7 @@ RoleMap BuildSubroleMap() {
  {ax::mojom::Role::kMain, @"AXLandmarkMain"},
  {ax::mojom::Role::kMarquee, @"AXApplicationMarquee"},
  {ax::mojom::Role::kMath, @"AXDocumentMath"},
+ {ax::mojom::Role::kMathMLMath, @"AXDocumentMath"},
  {ax::mojom::Role::kNavigation, @"AXLandmarkNavigation"},
  {ax::mojom::Role::kNote, @"AXDocumentNote"},
  {ax::mojom::Role::kRegion, @"AXLandmarkRegion"},

ui/accessibility/platform/ax_platform_node_win.cc

@@ -5537,6 +5537,7 @@ int AXPlatformNodeWin::MSAARole() {
  return ROLE_SYSTEM_ANIMATION;
 
  case ax::mojom::Role::kMath:
+ case ax::mojom::Role::kMathMLMath:
  return ROLE_SYSTEM_EQUATION;
 
  case ax::mojom::Role::kMenu:
@@ -6367,6 +6368,7 @@ std::wstring AXPlatformNodeWin::UIAAriaRole() {
  return L"marquee";
 
  case ax::mojom::Role::kMath:
+ case ax::mojom::Role::kMathMLMath:
  return L"group";
 
  case ax::mojom::Role::kMenu:
@@ -7030,6 +7032,7 @@ LONG AXPlatformNodeWin::ComputeUIAControlType() { // NOLINT(runtime/int)
  return UIA_TextControlTypeId;
 
  case ax::mojom::Role::kMath:
+ case ax::mojom::Role::kMathMLMath:
  return UIA_GroupControlTypeId;
 
  case ax::mojom::Role::kMenu: