Mac accessibility: only use AXTitleUIElement if that element has valid text.

content/browser/accessibility/browser_accessibility_cocoa.mm

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <execinfo.h>
 #include <stddef.h>
 #include <stdint.h>
 
 #import "content/browser/accessibility/browser_accessibility_cocoa.h"
 
@@ skipping 754 matching lines @@
 }
 
 - (NSString*)description {
   if (![self instanceActive])
     return nil;
 
   // Mac OS X wants static text exposed in AXValue.
   if ([self shouldExposeNameInAXValue])
     return @"";
 
-  // If the name came from a single related element and it's present in the
-  // tree, it will be exposed in AXTitleUIElement.
-  std::vector<int32_t> labelledby_ids =
-      browserAccessibility_->GetIntListAttribute(ui::AX_ATTR_LABELLEDBY_IDS);
+  // If we're exposing the title in TitleUIElement, don't also redundantly
+  // expose it in AXDescription.
+  if ([self shouldExposeTitleUIElement])
+    return @"";
+
   ui::AXNameFrom nameFrom = static_cast<ui::AXNameFrom>(
       browserAccessibility_->GetIntAttribute(ui::AX_ATTR_NAME_FROM));
   std::string name = browserAccessibility_->GetStringAttribute(
       ui::AX_ATTR_NAME);
-
-  // VoiceOver ignores titleUIElement on non-control AX nodes, so this special
-  // case expressly returns a nonempty text name for these nodes.
-  if (nameFrom == ui::AX_NAME_FROM_RELATED_ELEMENT &&
-      labelledby_ids.size() == 1 &&
-      browserAccessibility_->manager()->GetFromID(labelledby_ids[0]) &&
-      !browserAccessibility_->IsControl()) {
-    return base::SysUTF8ToNSString(name);
-  }
-
   if (!name.empty()) {
     // On Mac OS X, the accessible name of an object is exposed as its
     // title if it comes from visible text, and as its description
     // otherwise, but never both.
     if (nameFrom == ui::AX_NAME_FROM_CONTENTS ||
         nameFrom == ui::AX_NAME_FROM_RELATED_ELEMENT ||
         nameFrom == ui::AX_NAME_FROM_VALUE) {
       return @"";
     } else {
       return base::SysUTF8ToNSString(name);
@@ skipping 427 matching lines @@
     case ui::AX_ROLE_LIST_BOX_OPTION:
     case ui::AX_ROLE_LIST_MARKER:
     case ui::AX_ROLE_MENU_LIST_OPTION:
     case ui::AX_ROLE_STATIC_TEXT:
       return true;
     default:
       return false;
   }
 }
 
+// Returns true if this object should expose its accessible name using
+// AXTitleUIElement rather than AXTitle or AXDescription. We only do
+// this if it's a control, if there's a single label, and the label has
+// nonempty text.
+// internal
+- (BOOL)shouldExposeTitleUIElement {
+  // VoiceOver ignores TitleUIElement if the element isn't a control.
+  if (!browserAccessibility_->IsControl())
+    return false;
+
+  ui::AXNameFrom nameFrom = static_cast<ui::AXNameFrom>(
+      browserAccessibility_->GetIntAttribute(ui::AX_ATTR_NAME_FROM));
+  if (nameFrom != ui::AX_NAME_FROM_RELATED_ELEMENT)
+    return false;
+
+  std::vector<int32_t> labelledby_ids =
+  browserAccessibility_->GetIntListAttribute(ui::AX_ATTR_LABELLEDBY_IDS);
+  if (labelledby_ids.size() != 1)
+    return false;
+
+  BrowserAccessibility* label =
+      browserAccessibility_->manager()->GetFromID(labelledby_ids[0]);
+  if (!label)
+    return false;
+
+  std::string labelName = label->GetStringAttribute(ui::AX_ATTR_NAME);
+  return !labelName.empty();
+}
+
 // internal
 - (content::BrowserAccessibilityDelegate*)delegate {
   return [self instanceActive] ? browserAccessibility_->manager()->delegate()
                                : nil;
 }
 
 - (content::BrowserAccessibility*)browserAccessibility {
   return browserAccessibility_;
 }
 
@@ skipping 459 matching lines @@
   return tabSubtree;
 }
 
 - (NSString*)title {
   if (![self instanceActive])
     return nil;
   // Mac OS X wants static text exposed in AXValue.
   if ([self shouldExposeNameInAXValue])
     return @"";
 
-  // If the name came from a single related element and it's present in the
-  // tree, it will be exposed in AXTitleUIElement.
-  std::vector<int32_t> labelledby_ids =
-      browserAccessibility_->GetIntListAttribute(ui::AX_ATTR_LABELLEDBY_IDS);
-  ui::AXNameFrom nameFrom = static_cast<ui::AXNameFrom>(
-      browserAccessibility_->GetIntAttribute(ui::AX_ATTR_NAME_FROM));
-  if (nameFrom == ui::AX_NAME_FROM_RELATED_ELEMENT &&
-      labelledby_ids.size() == 1 &&
-      browserAccessibility_->manager()->GetFromID(labelledby_ids[0])) {
+  // If we're exposing the title in TitleUIElement, don't also redundantly
+  // expose it in AXDescription.
+  if ([self shouldExposeTitleUIElement])
     return @"";
-  }
 
   // On Mac OS X, the accessible name of an object is exposed as its
   // title if it comes from visible text, and as its description
   // otherwise, but never both.
+  ui::AXNameFrom nameFrom = static_cast<ui::AXNameFrom>(
+      browserAccessibility_->GetIntAttribute(ui::AX_ATTR_NAME_FROM));
   if (nameFrom == ui::AX_NAME_FROM_CONTENTS ||
       nameFrom == ui::AX_NAME_FROM_RELATED_ELEMENT ||
       nameFrom == ui::AX_NAME_FROM_VALUE) {
     return NSStringForStringAttribute(
         browserAccessibility_, ui::AX_ATTR_NAME);
   }
 
   return nil;
 }
 
 - (id)titleUIElement {
   if (![self instanceActive])
     return nil;
+  if (![self shouldExposeTitleUIElement])
+    return nil;
+
   std::vector<int32_t> labelledby_ids =
       browserAccessibility_->GetIntListAttribute(ui::AX_ATTR_LABELLEDBY_IDS);
   ui::AXNameFrom nameFrom = static_cast<ui::AXNameFrom>(
       browserAccessibility_->GetIntAttribute(ui::AX_ATTR_NAME_FROM));
   if (nameFrom == ui::AX_NAME_FROM_RELATED_ELEMENT &&
       labelledby_ids.size() == 1) {
     BrowserAccessibility* titleElement =
         browserAccessibility_->manager()->GetFromID(labelledby_ids[0]);
     if (titleElement)
       return ToBrowserAccessibilityCocoa(titleElement);
@@ skipping 1103 matching lines @@
   if (![self instanceActive])
     return [super hash];
   return browserAccessibility_->GetId();
 }
 
 - (BOOL)accessibilityShouldUseUniqueId {
   return YES;
 }
 
 @end