Potential dead object access in media::PlayerImplementation::Private

[Alberto Aguirre]

The engine state changed signal slot issues calls like these:

wakelock_timeout.reset(new timeout(4000, true, std::bind(&Private::clear_wakelock,
                                    this, std::placeholders::_1), current_wakelock_type()));

Which launches detached threads that accesses the media::PlayerImplementation::Private object instance.

If media::PlayerImplementation is destroyed before these threads get a chance to run, chaos will ensue...