exo: Fix crash in out-of-order destruction of Gamepad

components/exo/gamepad.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_GAMEPAD_H_
 #define COMPONENTS_EXO_GAMEPAD_H_
 
 #include <memory>
 
 #include "base/macros.h"
@@ skipping 12 matching lines @@
     base::Callback<std::unique_ptr<device::GamepadDataFetcher>()>;
 
 // This class represents one or more gamepads, it uses a background thread
 // for polling gamepad devices and notifies the GamepadDelegate of any
 // changes.
 class Gamepad : public aura::client::FocusChangeObserver {
  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.
   Gamepad(GamepadDelegate* delegate,
-          base::SingleThreadTaskRunner* polling_task_runner);
+          scoped_refptr<base::SingleThreadTaskRunner> polling_task_runner);

[reveman, 2016/07/19 17:16:53]

This just adds ref-count churn. Passing a raw pointer as before is fine.

   // Allows test cases to specify a CreateGamepadDataFetcherCallback that
   // overrides the default GamepadPlatformDataFetcher.
   Gamepad(GamepadDelegate* delegate,
-          base::SingleThreadTaskRunner* polling_task_runner,
+          scoped_refptr<base::SingleThreadTaskRunner> polling_task_runner,

[reveman, 2016/07/19 17:16:53]

ditto

           CreateGamepadDataFetcherCallback create_fetcher_callback);
   ~Gamepad() override;
 
   // Overridden aura::client::FocusChangeObserver:
   void OnWindowFocused(aura::Window* gained_focus,
                        aura::Window* lost_focus) override;
 
  private:
   class ThreadSafeGamepadChangeFetcher;
 
@@ skipping 14 matching lines @@
   base::ThreadChecker thread_checker_;
 
   base::WeakPtrFactory<Gamepad> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(Gamepad);
 };
 
 }  // namespace exo
 
 #endif  // COMPONENTS_EXO_GAMEPAD_H_