Add runtime setting to force passive event listeners.

third_party/WebKit/Source/web/WebSettingsImpl.cpp

Index: third_party/WebKit/Source/web/WebSettingsImpl.cpp
diff --git a/third_party/WebKit/Source/web/WebSettingsImpl.cpp b/third_party/WebKit/Source/web/WebSettingsImpl.cpp
index da9e03de78b3ad4173367b56b132c0a8a4f6a61d..54d06cbdd3874c7b533fb09d6e31f921f1d4d105 100644
--- a/third_party/WebKit/Source/web/WebSettingsImpl.cpp
+++ b/third_party/WebKit/Source/web/WebSettingsImpl.cpp
@@ -627,6 +627,11 @@ void WebSettingsImpl::setStrictlyBlockBlockableMixedContent(bool enabled)
     m_settings->setStrictlyBlockBlockableMixedContent(enabled);
 }
 
+void WebSettingsImpl::setPassiveEventListenerDefault(PassiveEventListenerDefault defaultValue)
+{
+    m_settings->setPassiveListenerDefault(static_cast<PassiveListenerDefault>(defaultValue));
+}
+
 void WebSettingsImpl::setPasswordEchoEnabled(bool flag)
 {
     m_settings->setPasswordEchoEnabled(flag);