A helper class for managing a PlaybackControlsRow
and PlaybackGlueHost that implements a
recommended approach to handling standard playback control actions such as play/pause,
fast forward/rewind at progressive speed levels, and skip to next/previous.
Base class for abstraction of media play/pause feature. A subclass of PlaybackGlue will contain
implementation of Media Player or a connection to playback Service. App initializes
PlaybackGlue subclass, associated it with a PlaybackGlueHost. PlaybackGlueHost
is typically implemented by a Fragment or an Activity, it provides the environment to render UI
for PlaybackGlue object, it optionally provides SurfaceHolder via SurfaceHolderGlueHost
to render video. A typical PlaybackGlue should release resources (e.g. MediaPlayer or connection
to playback Service) in onDetachedFromHost().
onDetachedFromHost() is called in two cases: