Changed DeviceDataManager to be able to create multiple instances for the purposes of test.

ui/events/devices/device_data_manager.h

Index: ui/events/devices/device_data_manager.h
diff --git a/ui/events/devices/device_data_manager.h b/ui/events/devices/device_data_manager.h
index d8ede81f22d885982daf0997bcbba8d56b94df00..2975b9fe77eddd452a59d76ad388778f9b4e5bb4 100644
--- a/ui/events/devices/device_data_manager.h
+++ b/ui/events/devices/device_data_manager.h
@@ -30,6 +30,7 @@ class EVENTS_DEVICES_EXPORT DeviceDataManager
   ~DeviceDataManager() override;
 
   static void CreateInstance();
+  static void DeleteInstance();
   static DeviceDataManager* GetInstance();
   static bool HasInstance();
 
@@ -63,6 +64,8 @@ class EVENTS_DEVICES_EXPORT DeviceDataManager
 
   static DeviceDataManager* instance();
 
+  static void set_instance(DeviceDataManager* instance);
+
   // DeviceHotplugEventObserver:
   void OnTouchscreenDevicesUpdated(
       const std::vector<TouchscreenDevice>& devices) override;