I've gone through everything on http://www.chromium.org/chromium-os/android-apps and also watched the IO video and there doesn't seem to be any mention of what the side-loading (and debugging) mechanism available for developing/testing Android apps on ChromeOS will be?
I know that ARC used adb on desktops but not Chromebooks
Given that the new implementation is different and its a full Android framework in a Linux container and has access to USB, will ADB be available for this prupose? Using ADB could also be useful for remote debugging since Devtools already runs an adb client
EDIT: As of 9 Aug 2016 there is now official documentation available.
Unless you are in Developer Mode, you won't be able to enable unknown sources. So in order to side load apps you will need to put your device into Developer Mode (instructions here - follow the steps for the Chromebook Pixel 2015).
Once you are in Dev Mode, go to Chrome Settings > App Settings > Security > Unknown sources (move to the right)
After enabling developer mode you can side load apps in one of 2 ways:
Here is a sample walkthru of setting up an ethernet connection for approach 3: