IOS/USB: Move scan thread logic into a separate class

This moves the scan thread logic and variables into a separate
ScanThread class. By turning ScanThread instances into members of the
most derived class, this ensures that the scan thread is always
properly stopped when the most derived class is destructed and fixes
a race condition that could cause the scan thread to call virtual
member functions from a derived class whose members have already
been destructed.

A drawback of this approach is that the scan thread must be the last
member variable, so this commit also adds static assertions to ensure
that the assumption stays valid.

0 files changed, 0 insertions, 0 deletions