ozone: Map TouchEvent::touch_id_ into expected range

ui/events/ozone/evdev/input_device_factory_evdev.h

 // Copyright 2014 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 UI_EVENTS_OZONE_EVDEV_INPUT_DEVICE_FACTORY_EVDEV_H_
 #define UI_EVENTS_OZONE_EVDEV_INPUT_DEVICE_FACTORY_EVDEV_H_
 
 #include <map>
 #include <set>
 #include <vector>
@@ skipping 67 matching lines @@
   // Open device at path & starting processing events (on UI thread).
   void AttachInputDevice(scoped_ptr<EventConverterEvdev> converter);
 
   // Close device at path (on UI thread).
   void DetachInputDevice(const base::FilePath& file_path);
 
   // Sync input_device_settings_ to attached devices.
   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();
   void NotifyKeyboardsUpdated();
   void NotifyTouchscreensUpdated();
   void NotifyMouseDevicesUpdated();
   void NotifyTouchpadDevicesUpdated();
 
   void SetIntPropertyForOneType(const EventDeviceType type,
                                 const std::string& name,
@@ skipping 22 matching lines @@
   // Number of pending device additions & device classes.
   int pending_device_changes_;
   bool touchscreen_list_dirty_;
   bool keyboard_list_dirty_;
   bool mouse_list_dirty_;
   bool touchpad_list_dirty_;
 
   // 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_;
 
   // Support weak pointers for attach & detach callbacks.
   base::WeakPtrFactory<InputDeviceFactoryEvdev> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(InputDeviceFactoryEvdev);
 };
 
 }  // namespace ui
 
 #endif  // UI_EVENTS_OZONE_EVDEV_INPUT_DEVICE_FACTORY_EVDEV_H_