It's actually there...Double click on the PDF. Then Choose "Pop Out".
No option to convert or not convert files uploaded to drive
I know +Chris Betcher (does the "+" work in Blogger?) was quite annoyed about losing the choice.... But here is an alternative way to look at it. In the old drive, it was critical to have the choice... Is it critical anymore? I don't think it is. Office files uploaded to drive default to being office files. Since they open natively in the browser and allows you to edit, the need to convert is no longer that important. Then if you want to collaborate with someone else, as soon as you press share, it converts it. Or if you want to convert, it's there under file.
I quite like the new drive....