Bug 1787686: Expose the URL of a link as its value, as well as the value of text/image leaf descendants. r=morgan

Differential Revision: https://phabricator.services.mozilla.com/D155810

accessible/generic/LocalAccessible.cpp

@@ -1367,6 +1367,10 @@ void LocalAccessible::DOMAttributeChanged(int32_t aNameSpaceID,
     SendCache(CacheDomain::Actions, CacheUpdateType::Update);
   }
 
+  if (aAttribute == nsGkAtoms::href) {
+    mDoc->QueueCacheUpdate(this, CacheDomain::Value);
+  }
+
   if (aAttribute == nsGkAtoms::aria_controls ||
       aAttribute == nsGkAtoms::aria_flowto) {
     mDoc->QueueCacheUpdate(this, CacheDomain::Relations);
@@ -3149,6 +3153,7 @@ already_AddRefed<AccAttributes> LocalAccessible::BundleFieldsForCache(
     // 1. Accessible is an HTML input type that holds a number.
     // 2. Accessible has a numeric value and an aria-valuetext.
     // 3. Accessible is an HTML input type that holds text.
+    // 4. Accessible is a link, in which case value is the target URL.
     // ... for all other cases we divine the value remotely.
     bool cacheValueText = false;
     if (HasNumericValue()) {
@@ -3161,7 +3166,7 @@ already_AddRefed<AccAttributes> LocalAccessible::BundleFieldsForCache(
                         mContent->AsElement()->HasAttr(
                             kNameSpaceID_None, nsGkAtoms::aria_valuetext));
     } else {
-      cacheValueText = IsTextField();
+      cacheValueText = IsTextField() || IsHTMLLink();
     }
 
     if (cacheValueText) {

accessible/ipc/RemoteAccessibleBase.cpp

@@ -276,6 +276,17 @@ void RemoteAccessibleBase<Derived>::Value(nsString& aValue) const {
       if (option) {
         option->Name(aValue);
       }
+      return;
+    }
+
+    if (IsTextLeaf() || IsImage()) {
+      if (const Accessible* actionAcc = ActionAncestor()) {
+        if (const_cast<Accessible*>(actionAcc)->State() & states::LINKED) {
+          // Text and image descendants of links expose the link URL as the
+          // value.
+          return actionAcc->Value(aValue);
+        }
+      }
     }
   }
 }

accessible/tests/browser/e10s/browser_caching_value.js

@@ -212,3 +212,37 @@ addAccessibleTask(
   },
   { iframe: true, remoteIframe: true }
 );
+
+/**
+ * Test caching of link URL values.
+ */
+addAccessibleTask(
+  `<a id="link" href="https://example.com/">Test</a>`,
+  async function(browser, docAcc) {
+    const link = findAccessibleChildByID(docAcc, "link");
+    is(link.value, "https://example.com/", "link initial value correct");
+    const textLeaf = link.firstChild;
+    is(textLeaf.value, "https://example.com/", "link initial value correct");
+
+    info("Changing link href");
+    await invokeSetAttribute(browser, "link", "href", "https://example.net/");
+    await untilCacheIs(
+      () => link.value,
+      "https://example.net/",
+      "link value correct after change"
+    );
+
+    info("Removing link href");
+    await invokeSetAttribute(browser, "link", "href");
+    await untilCacheIs(() => link.value, "", "link value empty after removal");
+
+    info("Setting link href");
+    await invokeSetAttribute(browser, "link", "href", "https://example.com/");
+    await untilCacheIs(
+      () => link.value,
+      "https://example.com/",
+      "link value correct after change"
+    );
+  },
+  { chrome: true, topLevel: true, iframe: true, remoteIframe: true }
+);