Reset the default value of touch event flag back to "Auto".

content/browser/renderer_host/render_view_host_impl.cc

Index: content/browser/renderer_host/render_view_host_impl.cc
diff --git a/content/browser/renderer_host/render_view_host_impl.cc b/content/browser/renderer_host/render_view_host_impl.cc
index fc1f18772cea21eada1fe8ba4c1007a7653c45fb..6bc9f032c35671a423c698b70ea58962750f23eb 100644
--- a/content/browser/renderer_host/render_view_host_impl.cc
+++ b/content/browser/renderer_host/render_view_host_impl.cc
@@ -450,12 +450,15 @@ WebPreferences RenderViewHostImpl::ComputeWebkitPrefs() {
   prefs.autoplay_experiment_mode = base::FieldTrialList::FindFullName(
       "MediaElementGestureOverrideExperiment");
 
-  prefs.touch_event_api_enabled =
-      !command_line.HasSwitch(switches::kTouchEvents) ||
-      command_line.GetSwitchValueASCII(switches::kTouchEvents) !=
-          switches::kTouchEventsDisabled;
   prefs.device_supports_touch = ui::GetTouchScreensAvailability() ==
                                 ui::TouchScreensAvailability::ENABLED;
+  prefs.touch_event_api_enabled =
+      (!command_line.HasSwitch(switches::kTouchEvents) ||
+       command_line.GetSwitchValueASCII(switches::kTouchEvents) ==
+           switches::kTouchEventsAuto)
+          ? prefs.device_supports_touch
+          : (command_line.GetSwitchValueASCII(switches::kTouchEvents) ==
+             switches::kTouchEventsEnabled);
   std::tie(prefs.available_pointer_types, prefs.available_hover_types) =
       ui::GetAvailablePointerAndHoverTypes();
   prefs.primary_pointer_type =