Bug 1395181 part 2: Support click handlers added to the root element. r=eeejay

Normally, we treat the body as the DOM node for a DocAccessible.
However, a click listener can be added to the root element; e.g. the html element.
We now treat a click listener added to the root element the same as if one were added to the body.

This required a change to nsAccessibilityService to use the DocAccessible when click listeners change for the root element so a cache update is pushed.
This change was made for the body also, since we weren't pushing a cache update for click listener changes on the body either.

Differential Revision: https://phabricator.services.mozilla.com/D144278

accessible/base/nsAccessibilityService.cpp

@@ -304,6 +304,10 @@ nsAccessibilityService::ListenersChanged(nsIArray* aEventChanges) {
 
       if (document) {
         LocalAccessible* acc = document->GetAccessible(content);
+        if (!acc && (content == document->GetContent() ||
+                     content == document->DocumentNode()->GetRootElement())) {
+          acc = document;
+        }
         if (!acc && nsCoreUtils::HasClickListener(content)) {
           // Create an accessible for a inaccessible element having click event
           // handler.

accessible/generic/DocAccessible.cpp

@@ -2616,3 +2616,26 @@ LocalAccessible* DocAccessible::GetAccessible(nsINode* aNode) const {
   return aNode == mDocumentNode ? const_cast<DocAccessible*>(this)
                                 : mNodeToAccessibleMap.Get(aNode);
 }
+
+bool DocAccessible::HasPrimaryAction() const {
+  if (HyperTextAccessible::HasPrimaryAction()) {
+    return true;
+  }
+  // mContent is normally the body, but there might be a click listener on the
+  // root.
+  dom::Element* root = mDocumentNode->GetRootElement();
+  if (mContent != root) {
+    return nsCoreUtils::HasClickListener(root);
+  }
+  return false;
+}
+
+void DocAccessible::ActionNameAt(uint8_t aIndex, nsAString& aName) {
+  aName.Truncate();
+  if (aIndex != 0) {
+    return;
+  }
+  if (HasPrimaryAction()) {
+    aName.AssignLiteral("click");
+  }
+}

accessible/generic/DocAccessible.h

@@ -84,6 +84,10 @@ class DocAccessible : public HyperTextAccessibleWrap,
 
   virtual nsRect RelativeBounds(nsIFrame** aRelativeFrame) const override;
 
+  // ActionAccessible
+  virtual bool HasPrimaryAction() const override;
+  virtual void ActionNameAt(uint8_t aIndex, nsAString& aName) override;
+
   // HyperTextAccessible
   virtual already_AddRefed<EditorBase> GetEditor() const override;
 

accessible/tests/browser/e10s/browser_caching_actions.js

@@ -170,9 +170,9 @@ addAccessibleTask(
     await _testActions("onclick_img", ["showlongdesc"]);
 
     // Remove 'href' from link and test linkable child
-    acc = findAccessibleChildByID(docAcc, "link1");
+    const link1Acc = findAccessibleChildByID(docAcc, "link1");
     is(
-      acc.firstChild.getActionName(0),
+      link1Acc.firstChild.getActionName(0),
       "click ancestor",
       "linkable child has click ancestor action"
     );
@@ -180,8 +180,29 @@ addAccessibleTask(
       let link1 = content.document.getElementById("link1");
       link1.removeAttribute("href");
     });
-    await untilCacheIs(() => acc.actionCount, 0, "link has no actions");
-    is(acc.firstChild.actionCount, 0, "linkable child's actions removed");
+    await untilCacheIs(() => link1Acc.actionCount, 0, "link has no actions");
+    is(link1Acc.firstChild.actionCount, 0, "linkable child's actions removed");
+
+    // Add a click handler to the body. Ensure it propagates to descendants.
+    await invokeContentTask(browser, [], () => {
+      content.document.body.onclick = () => {};
+    });
+    await untilCacheIs(() => docAcc.actionCount, 1, "Doc has 1 action");
+    await _testActions("link1", ["click ancestor"]);
+
+    await invokeContentTask(browser, [], () => {
+      content.document.body.onclick = null;
+    });
+    await untilCacheIs(() => docAcc.actionCount, 0, "Doc has no actions");
+    is(link1Acc.actionCount, 0, "link has no actions");
+
+    // Add a click handler to the root element. Ensure it propagates to
+    // descendants.
+    await invokeContentTask(browser, [], () => {
+      content.document.documentElement.onclick = () => {};
+    });
+    await untilCacheIs(() => docAcc.actionCount, 1, "Doc has 1 action");
+    await _testActions("link1", ["click ancestor"]);
   },
   {
     chrome: true,