MacViews a11y: Support the "Show menu" action in Textfield and Combobox.

ui/views/accessibility/native_view_accessibility_base.cc

Index: ui/views/accessibility/native_view_accessibility_base.cc
diff --git a/ui/views/accessibility/native_view_accessibility_base.cc b/ui/views/accessibility/native_view_accessibility_base.cc
index 49a06e54118e4c81f55d97c210fd9aa0efbacfd2..295548c8c2e31d61b13519c13aa0b89f62b4b425 100644
--- a/ui/views/accessibility/native_view_accessibility_base.cc
+++ b/ui/views/accessibility/native_view_accessibility_base.cc
@@ -89,6 +89,9 @@ const ui::AXNodeData& NativeViewAccessibilityBase::GetData() const {
   if (!view_->IsDrawn())
     data_.AddState(ui::AX_STATE_INVISIBLE);
 
+  if (view_->context_menu_controller())
+    data_.AddAction(ui::AX_ACTION_SHOW_CONTEXT_MENU);
+
   // Make sure this element is excluded from the a11y tree if there's a
   // focusable parent. All keyboard focusable elements should be leaf nodes.
   // Exceptions to this rule will themselves be accessibility focusable.