Allow gaming_seat to use ozone gamepad as back-end

components/exo/gaming_seat.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 COMPONENTS_EXO_GAMING_SEAT_H_
 #define COMPONENTS_EXO_GAMING_SEAT_H_
 
 #include <memory>
 
+#include "base/containers/flat_map.h"
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
 #include "base/sequenced_task_runner.h"
 #include "base/synchronization/lock.h"
 #include "base/threading/thread.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "components/exo/wm_helper.h"
 #include "device/gamepad/gamepad_data_fetcher.h"
 #include "ui/aura/client/focus_change_observer.h"
 
+#if defined(USE_OZONE_GAMEPAD)
+#include "ui/events/ozone/gamepad/gamepad_observer.h"
+
+namespace ui {
+class GamepadProviderOzone;
+}
+#endif
+
+namespace base {
+class Thread;
+}
+
 namespace exo {
 class GamingSeatDelegate;
 class GamepadDelegate;
 
 using CreateGamepadDataFetcherCallback =
     base::Callback<std::unique_ptr<device::GamepadDataFetcher>()>;
 
-// This class represents one gaming seat, it uses a background thread

[reveman, 2017/06/06 21:58:55]

Please keep a class description here in some form.

[jkwang, 2017/06/07 18:03:19]

Done.

-// for polling gamepad devices and notifies the corresponding GampadDelegate of
-// any changes.
-class GamingSeat : public WMHelper::FocusObserver {
+// TODO(jkwang) always use ozone_gamepad when ozone is default for all chrome os

[reveman, 2017/06/06 21:58:55]

nit: s/TODO(jkwang)/TODO(jkwang):", s/chrome os/Chrome OS/ and add a bug number.
Also why are we not just limiting gamepad interface support to ozone builds?

[jkwang, 2017/06/07 18:03:19]

Done.

+// build.

[reveman, 2017/06/06 21:58:55]

nit: s/build/builds/

[jkwang, 2017/06/07 18:03:19]

Done.

+class GamingSeat : public WMHelper::FocusObserver
+#if defined(USE_OZONE_GAMEPAD)
+                   ,
+                   public ui::GamepadObserver
+#endif
+{
  public:
-  // This class will post tasks to invoke the delegate on the thread runner
-  // which is associated with the thread that is creating this instance.
+  // This class will monitor gamepad connection change and manage gamepad

[reveman, 2017/06/06 21:58:55]

s/change/changes/

[jkwang, 2017/06/07 18:03:18]

Done.

+  // returned by gaming_seat_delegate.
   GamingSeat(GamingSeatDelegate* gaming_seat_delegate,
              base::SingleThreadTaskRunner* polling_task_runner);
 
-  // Allows test cases to specify a CreateGamepadDataFetcherCallback that
-  // overrides the default GamepadPlatformDataFetcher.
-  GamingSeat(GamingSeatDelegate* gaming_seat_delegate,
-             base::SingleThreadTaskRunner* polling_task_runner,
-             CreateGamepadDataFetcherCallback create_fetcher_callback);
-
   ~GamingSeat() override;
 
-  // Overridden WMHelper::FocusObserver:
+  // Overridden from WMHelper::FocusObserver:
   void OnWindowFocused(aura::Window* gained_focus,
                        aura::Window* lost_focus) override;
 
+#if defined(USE_OZONE_GAMEPAD)
+  // Overridden from ui::GamepadObserver:
+  void OnGamepadDevicesUpdated() override;
+  void OnGamepadEvent(const ui::GamepadEvent& event) override;
+#endif
+
  private:
+  // The delegate that handles gamepad_added.
+  GamingSeatDelegate* const delegate_;
+
+#if defined(USE_OZONE_GAMEPAD)
+  // Contains the delegate for each gamepad device.
+  base::flat_map<int, GamepadDelegate*> gamepads_;
+
+  // Cached pointer to GamepadProviderOzone.
+  ui::GamepadProviderOzone* gamepad_provider_;

[reveman, 2017/06/06 21:58:55]

why do we need this? please avoid caching a simple pointer that if possible so
we don't have to worry about it becoming invalid

[jkwang, 2017/06/07 18:03:19]

It is suggested here.
https://cs.chromium.org/chromium/src/base/memory/singleton.h?l=215

[reveman, 2017/06/07 20:29:45]

16ns on my P4/2.8GHz is not worth micro optimizing for imo.

[jkwang, 2017/06/07 22:01:45]

Done.

+#else
   class ThreadSafeGamepadChangeFetcher;
 
   // Processes updates of gamepad data and passes changes on to delegate.
   void ProcessGamepadChanges(int index, const device::Gamepad new_pad);
 
   // Private implementation of methods and resources that are used on the
   // polling thread.
   scoped_refptr<ThreadSafeGamepadChangeFetcher> gamepad_change_fetcher_;
 
-  // The delegate that handles gamepad_added.
-  GamingSeatDelegate* const delegate_;
-
   // The delegate instances that all other events are dispatched to.
   GamepadDelegate* gamepad_delegates_[device::Gamepads::kItemsLengthCap];
 
   // The current state of the gamepad represented by this instance.
   device::Gamepads pad_state_;
 
   // ThreadChecker for the origin thread.
-  base::ThreadChecker thread_checker_;
+  THREAD_CHECKER(thread_checker_);
 
   base::WeakPtrFactory<GamingSeat> weak_ptr_factory_;
+#endif
 
   DISALLOW_COPY_AND_ASSIGN(GamingSeat);
 };
 
 }  // namespace exo
 
 #endif  // COMPONENTS_EXO_GAMING_SEAT_H_