I am trying to launch my custom receiver application from the Chrome browser. The first step in doing so appears to add a receiver listener for the activity type I\'m intere
Yes activityType is your AppID. This works for me.
It seems that the extension-injected code may scan the network for possible devices AND what Apps/"Activities" are available. When you whitelisted your device by serial number, Google associated that with an AppID as being allowed to be a "receiver" for it.
For example, the string "YouTube" works of course, and both of my devices were sent into the onReceiverList callback. If I changed activityType to my AppID, then only my developer whitelisted device would show up. If I changed activityType to a random string, no devices show up.