Refactor Udev device support in Ozone and add a DRM hotplug monitor

ui/events/ozone/device/device_manager.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_DEVICE_DEVICE_MANAGER_H_
+#define UI_EVENTS_OZONE_DEVICE_DEVICE_MANAGER_H_
+
+#include "base/memory/scoped_ptr.h"
+#include "ui/events/events_export.h"
+
+namespace ui {
+
+class DeviceEventObserver;
+
+class EVENTS_EXPORT DeviceManager {
+ public:
+  virtual ~DeviceManager() {}
+
+  // Scans the currently available devices and notifies |observer| for each
+  // device found. If also registering for notifications through AddObserver(),
+  // the scan should happen after the registration otherwise the observer may
+  // miss events.
+  virtual void ScanDevices(DeviceEventObserver* observer) = 0;
+
+  // Registers |observer| for device event notifications.
+  virtual void AddObserver(DeviceEventObserver* observer) = 0;
+
+  // Removes |observer| from the list of observers notified.
+  virtual void RemoveObserver(DeviceEventObserver* observer) = 0;
+};
+
+EVENTS_EXPORT scoped_ptr<DeviceManager> CreateDeviceManager();
+
+}  // namespace ui
+
+#endif  // UI_EVENTS_OZONE_DEVICE_DEVICE_MANAGER_H_