Init AXRelationCache with the nodes already in the document.

Bug: 999236
Change-Id: I85ebdf7da06874cb55672fab6ec7071144858418
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1825958Reviewed-by: Aaron Leventhal <aleventhal@chromium.org>
Commit-Queue: Dominic Mazzoni <dmazzoni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#704259}

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

@@ -121,6 +121,7 @@ AXObjectCacheImpl::AXObjectCacheImpl(Document& document)
     AddPermissionStatusListener();
   documents_.insert(&document);
   document.View()->RegisterForLifecycleNotifications(this);
+  relation_cache_->Init();
 }
 
 AXObjectCacheImpl::~AXObjectCacheImpl() {

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

@@ -396,5 +396,55 @@ TEST_F(AccessibilityTest, CheckNoDuplicateChildren) {
   ASSERT_EQ(ax_select->FirstChild()->ChildCount(), 1);
 }
 
+TEST_F(AccessibilityTest, InitRelationCache) {
+  // All of the other tests already have accessibility initialized
+  // first, but we don't want to in this test.
+  //
+  // Get rid of the AXContext so the AXObjectCache is destroyed.
+  ax_context_.reset(nullptr);
+
+  SetBodyInnerHTML(R"HTML(
+      <ul id="ul" aria-owns="li"></ul>
+      <label for="a"></label>
+      <input id="a">
+      <input id="b">
+      <div role="section" id="div">
+        <li id="li"></li>
+      </div>
+    )HTML");
+
+  // Now recreate an AXContext, simulating what happens if accessibility
+  // is enabled after the document is loaded.
+  ax_context_.reset(new AXContext(GetDocument()));
+
+  const AXObject* root = GetAXRootObject();
+  ASSERT_NE(nullptr, root);
+  const AXObject* input_a = GetAXObjectByElementId("a");
+  ASSERT_NE(nullptr, input_a);
+  const AXObject* input_b = GetAXObjectByElementId("b");
+  ASSERT_NE(nullptr, input_b);
+
+  EXPECT_TRUE(
+      GetAXObjectCache().MayHaveHTMLLabel(ToHTMLElement(*input_a->GetNode())));
+  EXPECT_FALSE(
+      GetAXObjectCache().MayHaveHTMLLabel(ToHTMLElement(*input_b->GetNode())));
+
+  // Note: retrieve the LI first and check that its parent is not
+  // the paragraph element. If we were to retrieve the UL element,
+  // that would trigger the aria-owns check and wouln't allow us to
+  // test whether the relation cache was initialized.
+  const AXObject* li = GetAXObjectByElementId("li");
+  ASSERT_NE(nullptr, li);
+
+  const AXObject* div = GetAXObjectByElementId("div");
+  ASSERT_NE(nullptr, div);
+  EXPECT_NE(li->ParentObjectUnignored(), div);
+
+  const AXObject* ul = GetAXObjectByElementId("ul");
+  ASSERT_NE(nullptr, ul);
+
+  EXPECT_EQ(li->ParentObjectUnignored(), ul);
+}
+
 }  // namespace test
 }  // namespace blink

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

@@ -5,6 +5,7 @@
 #include "third_party/blink/renderer/modules/accessibility/ax_relation_cache.h"
 
 #include "base/memory/ptr_util.h"
+#include "third_party/blink/renderer/core/dom/element_traversal.h"
 #include "third_party/blink/renderer/core/html/forms/html_label_element.h"
 
 namespace blink {
@@ -16,6 +17,24 @@ AXRelationCache::AXRelationCache(AXObjectCacheImpl* object_cache)
 
 AXRelationCache::~AXRelationCache() = default;
 
+void AXRelationCache::Init() {
+  // Init the relation cache with elements already in the document.
+  Document& document = object_cache_->GetDocument();
+  for (Element& element :
+       ElementTraversal::DescendantsOf(*document.documentElement())) {
+    const auto& id = element.FastGetAttribute(kForAttr);
+    if (!id.IsEmpty())
+      all_previously_seen_label_target_ids_.insert(id);
+
+    if (element.FastHasAttribute(kAriaOwnsAttr)) {
+      if (AXObject* obj = object_cache_->GetOrCreate(&element)) {
+        obj->ClearChildren();
+        obj->AddChildren();
+      }
+    }
+  }
+}
+
 bool AXRelationCache::IsAriaOwned(const AXObject* child) const {
   return aria_owned_child_to_owner_mapping_.Contains(child->AXObjectID());
 }
@@ -271,6 +290,7 @@ void AXRelationCache::TextChanged(AXObject* object) {
 
 void AXRelationCache::LabelChanged(Node* node) {
   const auto& id = To<HTMLElement>(node)->FastGetAttribute(kForAttr);
+  LOG(ERROR) << "LabelChanged " << id;
   if (!id.IsEmpty()) {
     all_previously_seen_label_target_ids_.insert(id);
     if (auto* control = To<HTMLLabelElement>(node)->control())

third_party/blink/renderer/modules/accessibility/ax_relation_cache.h

@@ -22,6 +22,9 @@ class AXRelationCache {
   explicit AXRelationCache(AXObjectCacheImpl*);
   virtual ~AXRelationCache();
 
+  // Scan the initial document.
+  void Init();
+
   // Returns true if the given object's position in the tree was due to
   // aria-owns.
   bool IsAriaOwned(const AXObject*) const;

third_party/blink/renderer/modules/accessibility/testing/accessibility_test.h

@@ -44,12 +44,13 @@ class AccessibilityTest : public RenderingTest {
 
   std::string PrintAXTree() const;
 
+ protected:
+  std::unique_ptr<AXContext> ax_context_;
+
  private:
   std::ostringstream& PrintAXTreeHelper(std::ostringstream&,
                                         const AXObject* root,
                                         size_t level) const;
-
-  std::unique_ptr<AXContext> ax_context_;
 };
 
 }  // namespace test