Moving input device hotplug event processing outside of ui/display

ui/events/device_data_manager.cc

 // 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.
 
 #include "ui/events/device_data_manager.h"
 
 #include "base/at_exit.h"
 #include "base/bind.h"
 #include "base/logging.h"
 #include "ui/gfx/display.h"
@@ skipping 58 matching lines @@
     *y = point.y();
   }
 }
 
 int64_t DeviceDataManager::GetDisplayForTouchDevice(int touch_device_id) const {
   if (IsTouchDeviceIdValid(touch_device_id))
     return touch_device_to_display_map_[touch_device_id];
   return gfx::Display::kInvalidDisplayID;
 }
 
+std::vector<TouchscreenDevice> DeviceDataManager::GetTouchscreenDevices() {
+  return std::vector<TouchscreenDevice>();
+}
+
+void DeviceDataManager::AddObserver(InputDeviceEventObserver* observer) {
+  observers_.AddObserver(observer);
+}
+
+void DeviceDataManager::RemoveObserver(InputDeviceEventObserver* observer) {
+  observers_.RemoveObserver(observer);
+}
+
 }  // namespace ui