Add new InputDeviceManager interface.

ui/events/devices/input_device_manager.h

+// Copyright 2016 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_DEVICES_INPUT_DEVICE_MANAGER_H_
+#define UI_EVENTS_DEVICES_INPUT_DEVICE_MANAGER_H_
+
+#include <vector>
+
+#include "base/macros.h"
+#include "ui/events/devices/events_devices_export.h"
+#include "ui/events/devices/input_device.h"
+#include "ui/events/devices/input_device_event_observer.h"
+#include "ui/events/devices/touchscreen_device.h"
+
+namespace ui {
+
+// Interface to query available input devices. Holds a static pointer to an
+// implementation that provides this service. The implementation could be
+// DeviceDataManager or something that mirrors the necessary state if
+// DeviceDataManager is in a different process.
+class EVENTS_DEVICES_EXPORT InputDeviceManager {
+ public:
+  InputDeviceManager() {}
+
+  static InputDeviceManager* GetInstance();
+  static bool HasInstance();
+
+  virtual const std::vector<InputDevice>& GetKeyboardDevices() const = 0;
+  virtual const std::vector<TouchscreenDevice>& GetTouchscreenDevices()
+      const = 0;
+  virtual const std::vector<InputDevice>& GetMouseDevices() const = 0;
+  virtual const std::vector<InputDevice>& GetTouchpadDevices() const = 0;
+
+  virtual bool AreDeviceListsComplete() const = 0;
+  virtual bool AreTouchscreensEnabled() const = 0;
+
+  virtual void AddObserver(InputDeviceEventObserver* observer) = 0;
+  virtual void RemoveObserver(InputDeviceEventObserver* observer) = 0;
+
+ protected:
+  // Sets the instance. This should only be set once per process.
+  static void SetInstance(InputDeviceManager* instance);
+
+  // Clears the instance. InputDeviceManager doesn't own the instance and won't
+  // destroy it, so it should be cleared before it is destroyed elsewhere.
+  static void ClearInstance();
+
+ private:
+  static InputDeviceManager* instance_;  // Not owned.
+
+  DISALLOW_COPY_AND_ASSIGN(InputDeviceManager);
+};
+
+}  // namespace ui
+
+#endif  // UI_EVENTS_DEVICES_INPUT_DEVICE_MANAGER_H_