This post replies very well to the question \"How to get Advertising ID in android?\"...
but not how to use it.
I would like to know
It appears that the name of the parameter is "adid" for Android (and not "aaid"), as demonstrated by the screenshot below (request made by the GA SDK in a demo app).
It also appears (you see it on the screenshot) that the "ate" parameter must be sent with the advertising ID (ate=1 if the ads targeting is ON ; ate=0 if ads targeting in OFF) for the advertising ID to be taken into consideration by Google Analytics.
This implementation was tested and I can confirm that it works.