ozone: evdev: Add gamepad support

ui/events/ozone/gamepad/gamepad_provider_ozone.h

+// Copyright 2017 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_GAMEPAD_GAMEPAD_PROVIDER_OZONE_H_
+#define UI_EVENTS_OZONE_GAMEPAD_GAMEPAD_PROVIDER_OZONE_H_
+
+#include <set>
+#include <vector>
+#include "base/macros.h"
+#include "base/time/time.h"
+#include "ui/events/devices/input_device.h"
+#include "ui/events/ozone/evdev/events_ozone_evdev_export.h"
+#include "ui/events/ozone/gamepad/gamepad_observer.h"
+
+namespace base {
+template <typename T>
+struct DefaultSingletonTraits;
+}
+
+namespace ui {
+
+class EVENTS_OZONE_EVDEV_EXPORT GamepadProviderOzone {
+ public:
+  // Get the GamepadProviderOzone instance.
+  static GamepadProviderOzone* GetInstance();

[spang, 2017/04/21 05:38:47]

Can you get this through the existing OzonePlatform singleton rather than make a
new singleton (look at SystemInputInjector for an example).

[jkwang, 2017/04/25 21:16:41]

Will this result in a circular dependency? ui/ozone need to depende
ui/events/ozone to create GamepadProviderOzone instance and ui/events/ozone
depend ui/ozone because it need to GamepadProviderOzone to dispatch the events. 
I am not sure if moving GamepadProviderOzone to ui/ozone/public is a good idea?

+
+  // Dispatch GamepadDevicesUpdate event when gamepad device is connected or
+  // disconnected. This function must be called on UI thread.
+  void DispatchGamepadDevicesUpdated(std::vector<InputDevice> gamepad_devices);
+
+  // Dispatch button event when gamepad event is seen.
+  // Code is the index of gamepad button or gamepad axis defined in W3C standard
+  // gamepad.
+  // This function must be called on UI thread.
+  void DispatchGamepadEvent(const GamepadEvent& event);
+
+  // Add observer to gamepad provider. This function must be called on UI
+  // thread.
+  void AddGamepadObserver(GamepadObserver* observer);
+
+  // Remove observer from gamepad provider. This function must be called on UI
+  // thread.
+  void RemoveGamepadObserver(GamepadObserver* observer);
+
+  // Get the list of currently connected gamepad devices. This function must be
+  // called on UI thread.
+  std::vector<InputDevice> GetGamepadDevices();
+
+ private:
+  GamepadProviderOzone();
+
+  ~GamepadProviderOzone();
+
+  // Make SingletonTraits friend to enable singleton.
+  friend struct base::DefaultSingletonTraits<GamepadProviderOzone>;
+
+  // Registered observers will receive gamepad device update event and gamepad
+  // event.
+  std::set<GamepadObserver*> observers_;

[spang, 2017/04/21 05:38:47]

set is a binary search tree; this is overkill. Just use a vector or possibly
ObserverList

[jkwang, 2017/04/25 21:16:41]

Done.

+
+  // List of current connected gamepad events.
+  std::vector<InputDevice> gamepad_devices_;
+
+  DISALLOW_COPY_AND_ASSIGN(GamepadProviderOzone);
+};
+
+}  // namespace ui
+
+#endif  // UI_EVENTS_OZONE_GAMEPAD_GAMEPAD_PROVIDER_OZONE_H_