ozone: Map TouchEvent::touch_id_ into expected range

ui/events/ozone/evdev/input_device_factory_evdev.h

Index: ui/events/ozone/evdev/input_device_factory_evdev.h
diff --git a/ui/events/ozone/evdev/input_device_factory_evdev.h b/ui/events/ozone/evdev/input_device_factory_evdev.h
index 976de0dd7a5ec5659eb4a627821e47b39b6efe40..12b07b3cbdfedd5fd0174c45db826b3e0b2a4341 100644
--- a/ui/events/ozone/evdev/input_device_factory_evdev.h
+++ b/ui/events/ozone/evdev/input_device_factory_evdev.h
@@ -85,6 +85,9 @@ class EVENTS_OZONE_EVDEV_EXPORT InputDeviceFactoryEvdev {
   void ApplyInputDeviceSettings();
   void ApplyCapsLockLed();
 
+  // An offset must be applied to make the touch_id of events globally unique.
+  void ApplyTouchIdOffset(EventConverterEvdev* converter);
+
   // Update observers on device changes.
   void UpdateDirtyFlags(const EventConverterEvdev* converter);
   void NotifyDevicesUpdated();
@@ -127,6 +130,9 @@ class EVENTS_OZONE_EVDEV_EXPORT InputDeviceFactoryEvdev {
   // LEDs.
   bool caps_lock_led_enabled_;
 
+  // Next offset to use for touch id manipulation.
+  int next_touch_id_offset_;
+
   // Device settings. These primarily affect libgestures behavior.
   InputDeviceSettingsEvdev input_device_settings_;