Cache correct parent for AXObject of inline text boxes

When an AXInlineTextBox::NextOnLine()/PrevOnLine() is used, the parent
of any newly created AXInlineTextBox is not necessarily going to be
the same one. Compute the correct parent in all cases.

Addresses DCHECKs that are triggered in text-overflow:ellipsis cases.

Bug: 1168643
Change-Id: Ib41bc4617bee4761ccad35ad94ab33fb8be4ab43
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2639167Reviewed-by: Nektarios Paisios <nektar@chromium.org>
Commit-Queue: Aaron Leventhal <aleventhal@chromium.org>
Auto-Submit: Aaron Leventhal <aleventhal@chromium.org>
Cr-Commit-Position: refs/heads/master@{#846087}

content/browser/accessibility/dump_accessibility_tree_browsertest.cc

@@ -329,6 +329,11 @@ IN_PROC_BROWSER_TEST_P(DumpAccessibilityTreeTest,
   RunCSSTest(FILE_PATH_LITERAL("display-to-block.html"));
 }
 
+IN_PROC_BROWSER_TEST_P(DumpAccessibilityTreeTest,
+                       AccessibilityCSSTextOverflowEllipsis) {
+  RunCSSTest(FILE_PATH_LITERAL("text-overflow-ellipsis.html"));
+}
+
 IN_PROC_BROWSER_TEST_P(DumpAccessibilityTreeTest,
                        AccessibilityCSSInlinePositionRelative) {
   RunCSSTest(FILE_PATH_LITERAL("inline-position-relative.html"));

content/test/data/accessibility/css/text-overflow-ellipsis-expected-blink.txt

+rootWebArea
+++genericContainer ignored
+++++genericContainer ignored
+++++++genericContainer
+++++++++staticText name='SPAN NESTED INSIDE DIV'
+++++++++++inlineTextBox name='SPAN NESTED INSIDE DIV'
+++++++++++inlineTextBox name='SPAN NESTED INS'
+++++++++++inlineTextBox name='…'
+++++++++staticText name=' CONTAINER DIV'
+++++++++++inlineTextBox name=' CONTAINER DIV'

content/test/data/accessibility/css/text-overflow-ellipsis.html

+<style>
+  div {
+    overflow: hidden;
+    text-overflow: ellipsis;
+    white-space: nowrap;
+    width: 400px;
+  }
+
+  div, span {
+    outline: 1px solid;
+    font-size: 40px;
+    font-family: monospace;
+  }
+</style>
+
+<div><span>SPAN NESTED INSIDE DIV</span> CONTAINER DIV</div>

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

@@ -200,7 +200,7 @@ AXObject* AXInlineTextBox::NextOnLine() const {
   scoped_refptr<AbstractInlineTextBox> next_on_line =
       inline_text_box_->NextOnLine();
   if (next_on_line)
-    return AXObjectCache().GetOrCreate(next_on_line.get(), parent_);
+    return AXObjectCache().GetOrCreate(next_on_line.get(), nullptr);
 
   return nullptr;
 }
@@ -215,7 +215,7 @@ AXObject* AXInlineTextBox::PreviousOnLine() const {
   scoped_refptr<AbstractInlineTextBox> previous_on_line =
       inline_text_box_->PreviousOnLine();
   if (previous_on_line)
-    return AXObjectCache().GetOrCreate(previous_on_line.get(), parent_);
+    return AXObjectCache().GetOrCreate(previous_on_line.get(), nullptr);
 
   return nullptr;
 }

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

@@ -721,14 +721,17 @@ AXObject* AXObjectCacheImpl::GetOrCreate(AbstractInlineTextBox* inline_text_box,
   if (!inline_text_box)
     return nullptr;
 
-  DCHECK(parent);
+  if (!parent) {
+    Node* text_parent = inline_text_box->GetLineLayoutItem().GetNode();
+    DCHECK(text_parent);
+    DCHECK(IsA<Text>(text_parent));
+    parent = GetOrCreate(text_parent);
+    DCHECK(parent);
+  }
+
   if (AXObject* obj = Get(inline_text_box)) {
-    if (obj->CachedParentObject()) {
-      // It is possible that the parent AXObject has changed, but the related
-      // text node will be the same.
-      // TODO(alventhal) When is the cached parent different?
+    if (obj->CachedParentObject())
       DCHECK_EQ(obj->CachedParentObject()->GetNode(), parent->GetNode());
-    }
     obj->SetParent(parent);
     return obj;
   }

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

@@ -195,7 +195,7 @@ class MODULES_EXPORT AXObjectCacheImpl
   AXObject* GetOrCreate(Node*, AXObject* parent_if_known);
   AXObject* GetOrCreate(Node*);
   AXObject* GetOrCreate(const Node*);
-  AXObject* GetOrCreate(AbstractInlineTextBox*, AXObject* parent);
+  AXObject* GetOrCreate(AbstractInlineTextBox*, AXObject* parent_if_known);
 
   AXID GetAXID(Node*) override;
   Element* GetElementFromAXID(AXID) override;