Add runtime setting to force passive event listeners.

third_party/WebKit/Source/core/events/AddEventListenerOptionsDefaults.h

Index: third_party/WebKit/Source/core/events/AddEventListenerOptionsDefaults.h
diff --git a/third_party/WebKit/Source/core/events/AddEventListenerOptionsDefaults.h b/third_party/WebKit/Source/core/events/AddEventListenerOptionsDefaults.h
new file mode 100644
index 0000000000000000000000000000000000000000..8887c1e8ee532e53a76c800927d93da006a1fc98
--- /dev/null
+++ b/third_party/WebKit/Source/core/events/AddEventListenerOptionsDefaults.h
@@ -0,0 +1,25 @@
+// Copyright 2016 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.
+
+#ifndef AddEventListenerOptionsDefaults_h
+#define AddEventListenerOptionsDefaults_h
+
+namespace blink {
+
+// Defines the default for 'passive' field used in the AddEventListenerOptions interface
+// when javascript calls addEventListener.
+// |False| is the default specified in
+// https://dom.spec.whatwg.org/#dictdef-addeventlisteneroptions. However
+// specifying a different default value is useful in demonstrating the
+// power of passive event listeners.
+enum class PassiveListenerDefault {
+    False, // Default of false.
+    True, // Default of true.
+    DocumentTrue, // Default of true for document level elements, false otherwise.
+    ForceAllTrue // Force all values to be true even when specified.
+};
+
+} // namespace blink
+
+#endif // AddEventListenerOptionsDefaults_h