Add runtime setting to force passive event listeners.

content/renderer/render_view_impl.cc

Index: content/renderer/render_view_impl.cc
diff --git a/content/renderer/render_view_impl.cc b/content/renderer/render_view_impl.cc
index 3990452b0666a0bd22aa739ca90634f16634cc19..df3decf81cfa4d64c33f75b9fc1c8c215b09a726 100644
--- a/content/renderer/render_view_impl.cc
+++ b/content/renderer/render_view_impl.cc
@@ -723,6 +723,20 @@ void RenderViewImpl::Initialize(const ViewMsg_New_Params& params,
     selection_strategy = WebSettings::SelectionStrategyType::Direction;
   webview()->settings()->setSelectionStrategy(selection_strategy);
 
+  std::string passiveListenersDefault =
+      command_line.GetSwitchValueASCII(switches::kPassiveListenersDefault);
+  if (!passiveListenersDefault.empty()) {
+    WebSettings::PassiveEventListenerDefault passiveDefault =
+        WebSettings::PassiveEventListenerDefault::False;
+    if (passiveListenersDefault == "documentonlytrue")
+      passiveDefault = WebSettings::PassiveEventListenerDefault::DocumentTrue;
+    else if (passiveListenersDefault == "true")
+      passiveDefault = WebSettings::PassiveEventListenerDefault::True;
+    else if (passiveListenersDefault == "forcealltrue")
+      passiveDefault = WebSettings::PassiveEventListenerDefault::ForceAllTrue;
+    webview()->settings()->setPassiveEventListenerDefault(passiveDefault);
+  }
+
   ApplyBlinkSettings(command_line, webview()->settings());
 
   if (params.main_frame_routing_id != MSG_ROUTING_NONE) {