No ability to choose whether connected device has access to data

Ubuntu 15.04 r51

1. Flash or reset the phone.
2. Go through the setup process.
3. Connect the phone to a PC.

What happens: The PC automatically has access to the documents, photos, music etc on the phone.

What should happen: You should be prompted about whether you want to allow data transfer, or just want to charge the phone, to avoid juice jacking.

<https://wiki.ubuntu.com/Storage#storage-access>: "If you connect (or someone else connects) your locked phone to a device that tries to read its storage, it should be denied. If you connect the phone while unlocked: * If the device (as identified by its USB Vendor, ProdID, Rev, and SerialNumber) is not one that you have previously granted/denied storage access to, a prompt should appear with title 'Device Connected', primary text 'Make all your data accessible to this device?' and buttons 'Share Data' and 'Charge Only'..."