Mac accessibility: Add support for AXDOMIdentifier

content/browser/accessibility/accessibility_tree_formatter_mac.mm

Index: content/browser/accessibility/accessibility_tree_formatter_mac.mm
diff --git a/content/browser/accessibility/accessibility_tree_formatter_mac.mm b/content/browser/accessibility/accessibility_tree_formatter_mac.mm
index 283fe19c96642dbc9ae9614338c7a735e77b6523..a844a94bd0495709837cd85f71b85aa2b81fa98d 100644
--- a/content/browser/accessibility/accessibility_tree_formatter_mac.mm
+++ b/content/browser/accessibility/accessibility_tree_formatter_mac.mm
@@ -143,6 +143,9 @@ std::unique_ptr<base::Value> PopulateObject(id value) {
 }
 
 NSArray* BuildAllAttributesArray() {
+  // Note: clang-format tries to put multiple attributes on one line,
+  // but we prefer to have one per line for readability.
+  // clang-format off
   NSArray* array = [NSArray arrayWithObjects:
       NSAccessibilityRoleDescriptionAttribute,
       NSAccessibilityTitleAttribute,
@@ -167,6 +170,7 @@ NSArray* BuildAllAttributesArray() {
       @"AXARIASetSize",
       @"AXARIAPosInSet",
       NSAccessibilityColumnIndexRangeAttribute,
+      @"AXDOMIdentifier",
       @"AXDropEffects",
       NSAccessibilityEnabledAttribute,
       NSAccessibilityExpandedAttribute,
@@ -189,6 +193,8 @@ NSArray* BuildAllAttributesArray() {
       @"AXVisited",
       @"AXLinkedUIElements",
       nil];
+  // clang-format off
+
   return [array retain];
 }