Add Chromecast to data tracking

[barbeau]

Is your feature request related to a problem? Please describe.
We should track for each event values related to how the user experiences the music.

Describe the solution you'd like
Per today's discussion, we should also be recording for each event:

• Current volume
• Capture Device Type (Headset, Headphone, or Bluetooth)
• Chromecast in use or not for streaming music

[BumbleFlash]

@barbeau Thank you for opening this. About volume tracking, I found a couple of solutions on StackOverflow to be really useful for monitoring current volume especially when the user changes the volume while using the app. Feel free to let me know your thoughts on implementing something similar to this if not, the same.
https://stackoverflow.com/a/18273761 (getting current volume)
https://stackoverflow.com/a/15292255 (listening to the volume button and monitor when the user adjusts volume)

[barbeau]

I think we should do the following:

• For each player and UI event capture (from first link):
  • streamVolume()
  • streamVolumeDb()
  • streamMinVolume()
  • streamMaxVolume()
• For each volume button press/volume change, record a UI event
  • Looks like a better option may be MediaRouter.VolumeCallback? https://developer.android.com/reference/android/media/MediaRouter.VolumeCallback. See also https://stackoverflow.com/questions/62533627/is-there-a-way-in-android-to-listen-to-audio-volume-changes-only.

FYI, it looks like some of the other properties like connected output Bluetooth devices are accessible via AudioManager too:
https://developer.android.com/reference/android/media/AudioManager#getDevices(int)

...or for devices < API 23:
https://developer.android.com/reference/android/media/AudioManager#isBluetoothA2dpOn()

[BumbleFlash]

The current implementation tracks the volume and the device on which the user is currently listening to the song. The app can actively detect the device type even when the user continuously chooses to switch the output device.

However, per discussion today, we think the current implementation for tracking Bluetooth devices may not be the best way due to the variety of these devices. For example, measuring loudness could be a bit unreasonable when Android generalizes and classifies a Bluetooth speaker and a Bluetooth headphone as TYPE_BLUETOOTH_A2DP as the loudness measure could potentially be the same for both the devices for the same volume.