Initialize the Cast Context
The framework has a global singleton object, the CastContext, which coordinates all the framework's interactions.
Your app must implement the
OptionsProvider interface to supply options needed to initialize the
CastContext singleton. OptionsProvider provides an instance of
CastOptions which contains options that affect the behavior of the framework. The most important of these is the receiver application ID, which is used to filter discovery results and to launch the receiver app when a cast session is started.