Prevent popunders with the new auto-dismissing dialogs.

chrome/common/chrome_features.cc

Index: chrome/common/chrome_features.cc
diff --git a/chrome/common/chrome_features.cc b/chrome/common/chrome_features.cc
index 2b9424b4b74e7b06ab23ba34c4350b6d23234515..5550338c7c7a7b813f204ae6bda01b7cb778d044 100644
--- a/chrome/common/chrome_features.cc
+++ b/chrome/common/chrome_features.cc
@@ -14,6 +14,12 @@ const base::Feature kArcMemoryManagement{
     "ArcMemoryManagement", base::FEATURE_ENABLED_BY_DEFAULT};
 #endif  // defined(OS_CHROMEOS)
 
+#if !defined(OS_ANDROID) && !defined(OS_IOS)
+// Enables auto-dismissing JavaScript dialogs.
+const base::Feature kAutoDismissingDialogs{"AutoDismissingDialogs",
+                                           base::FEATURE_DISABLED_BY_DEFAULT};
+#endif
+
 #if defined(OS_WIN) || defined(OS_MACOSX)
 // Enables automatic tab discarding, when the system is in low memory state.
 const base::Feature kAutomaticTabDiscarding{"AutomaticTabDiscarding",