Bug 1773930: Expose xml-roles object attribute on cached RemoteAccessible. r=morgan

This also changes LocalAccessible::Attributes to ignore the edge case of an empty role attribute when calculating xml-roles.
This is consistent with how we handle the role attribute elsewhere (see aria::GetRoleMapIndex) and makes it easier to handle this consistently between local and remote.

Differential Revision: https://phabricator.services.mozilla.com/D149594

accessible/generic/LocalAccessible.cpp

@@ -1088,7 +1088,8 @@ already_AddRefed<AccAttributes> LocalAccessible::Attributes() {
   // 'xml-roles' attribute coming from ARIA.
   nsString xmlRoles;
   if (mContent->AsElement()->GetAttr(kNameSpaceID_None, nsGkAtoms::role,
-                                     xmlRoles)) {
+                                     xmlRoles) &&
+      !xmlRoles.IsEmpty()) {
     attributes->SetAttribute(nsGkAtoms::xmlroles, std::move(xmlRoles));
   } else if (nsAtom* landmark = LandmarkRole()) {
     // 'xml-roles' attribute for landmark.
@@ -3589,17 +3590,32 @@ already_AddRefed<AccAttributes> LocalAccessible::BundleFieldsForCache(
     if (mContent && mContent->IsElement()) {
       fields->SetAttribute(nsGkAtoms::tag, mContent->NodeInfo()->NameAtom());
 
+      dom::Element* el = mContent->AsElement();
       if (IsTextField() || IsDateTimeField()) {
         // Cache text input types. Accessible is recreated if this changes,
         // so it is considered immutable.
-        if (const nsAttrValue* attr =
-                mContent->AsElement()->GetParsedAttr(nsGkAtoms::type)) {
+        if (const nsAttrValue* attr = el->GetParsedAttr(nsGkAtoms::type)) {
           RefPtr<nsAtom> inputType = attr->GetAsAtom();
           if (inputType) {
             fields->SetAttribute(nsGkAtoms::textInputType, inputType);
           }
         }
       }
+
+      // Changing the role attribute currently re-creates the Accessible, so
+      // it's immutable in the cache.
+      if (const nsRoleMapEntry* roleMap = ARIARoleMap()) {
+        // Most of the time, the role attribute is a single, known role. We
+        // already send the map index, so we don't need to double up.
+        if (!el->AttrValueIs(kNameSpaceID_None, nsGkAtoms::role,
+                             roleMap->roleAtom, eIgnoreCase)) {
+          // Multiple roles or unknown roles are rare, so just send them as a
+          // string.
+          nsAutoString role;
+          el->GetAttr(kNameSpaceID_None, nsGkAtoms::role, role);
+          fields->SetAttribute(nsGkAtoms::role, std::move(role));
+        }
+      }
     }
 
     if (frame) {

accessible/ipc/RemoteAccessibleBase.cpp

@@ -821,6 +821,28 @@ already_AddRefed<AccAttributes> RemoteAccessibleBase<Derived>::Attributes() {
     if (auto ariaAttrs = GetCachedARIAAttributes()) {
       ariaAttrs->CopyTo(attributes);
     }
+
+    nsAutoString role;
+    mCachedFields->GetAttribute(nsGkAtoms::role, role);
+    if (role.IsEmpty()) {
+      bool found = false;
+      if (const nsRoleMapEntry* roleMap = ARIARoleMap()) {
+        if (roleMap->roleAtom != nsGkAtoms::_empty) {
+          // Single, known role.
+          attributes->SetAttribute(nsGkAtoms::xmlroles, roleMap->roleAtom);
+          found = true;
+        }
+      }
+      if (!found) {
+        if (nsAtom* landmark = LandmarkRole()) {
+          // Landmark role from markup; e.g. HTML <main>.
+          attributes->SetAttribute(nsGkAtoms::xmlroles, landmark);
+        }
+      }
+    } else {
+      // Unknown role or multiple roles.
+      attributes->SetAttribute(nsGkAtoms::xmlroles, std::move(role));
+    }
   }
 
   nsAutoString name;

accessible/tests/browser/e10s/browser_caching_attributes.js

@@ -371,3 +371,38 @@ addAccessibleTask(
   },
   { chrome: true, topLevel: true, iframe: true, remoteIframe: true }
 );
+
+/**
+ * Test support for the xml-roles attribute.
+ */
+addAccessibleTask(
+  `
+<div id="knownRole" role="main">knownRole</div>
+<div id="emptyRole" role="">emptyRole</div>
+<div id="unknownRole" role="foo">unknownRole</div>
+<div id="multiRole" role="foo main">multiRole</div>
+<main id="markup">markup</main>
+<main id="markupWithRole" role="banner">markupWithRole</main>
+<main id="markupWithEmptyRole" role="">markupWithEmptyRole</main>
+  `,
+  async function(browser, docAcc) {
+    const knownRole = findAccessibleChildByID(docAcc, "knownRole");
+    testAttrs(knownRole, { "xml-roles": "main" }, true);
+    const emptyRole = findAccessibleChildByID(docAcc, "emptyRole");
+    testAbsentAttrs(emptyRole, { "xml-roles": "" });
+    const unknownRole = findAccessibleChildByID(docAcc, "unknownRole");
+    testAttrs(unknownRole, { "xml-roles": "foo" }, true);
+    const multiRole = findAccessibleChildByID(docAcc, "multiRole");
+    testAttrs(multiRole, { "xml-roles": "foo main" }, true);
+    const markup = findAccessibleChildByID(docAcc, "markup");
+    testAttrs(markup, { "xml-roles": "main" }, true);
+    const markupWithRole = findAccessibleChildByID(docAcc, "markupWithRole");
+    testAttrs(markupWithRole, { "xml-roles": "banner" }, true);
+    const markupWithEmptyRole = findAccessibleChildByID(
+      docAcc,
+      "markupWithEmptyRole"
+    );
+    testAttrs(markupWithEmptyRole, { "xml-roles": "main" }, true);
+  },
+  { chrome: true, topLevel: true, iframe: true, remoteIframe: true }
+);