There are three parts of this issue:
New Unity GoogleVR package appeared so I decided to update it. After deleting old package and importing new one, I got a suggestion to delete 4 files which are using old api.
If I delete them Android app crashes on mobile phone with an error
Didn't find class "com.google.unity.GoogleUnityActivity"
. Note: one of the files it suggested to delete was /Assets/Plugins/Android/unitygvractivity.aar
which I assume has some significants.
If I don't delete it, Unity can't build the package: "unable to convert classes into dex format"
My question: how to include GoogleUnityActivity class so Unity doesn't complain. And why would Unity delete this class?
I'm using:
I found the cause!
After I updated GoogleVR asset folder, I forgot there's another one called Plugins. That folder contains manifest.xml files which defines which class to use. After completely reimporting the asset, problem solved it self!