Remove an obsolete TODO.

Change-Id: Ifd4dac47d3880aa80c4b360f1cbfccf8fa554c8e
internal/aetesting: Check the provided function's type more carefully.

Change-Id: I77a63d750bc68148f2a7f4c36e3f0a2ecf94c80d
Add internal/channel proto.

Change-Id: Ie0e0e7b295fe9057e5a9151cdb1c3595bd9fe450
Add channel package.

Change-Id: I7abda4c9c5269fbd63f38a05ac08b7e5d06ab3fc