UsbDeviceManager: set mUsbDataUnlocked=false on user switch

Make sure access to MTP data is relocked when a user switch occurs.

Bug: 25288494
Change-Id: I69dafc7f51b847f4dba1993a85fb1a51df1a5e37

services/usb/java/com/android/server/usb/UsbDeviceManager.java

@@ -715,6 +715,8 @@ public class UsbDeviceManager {
                         if (active && mCurrentUser != UserHandle.USER_NULL) {
                             Slog.v(TAG, "Current user switched to " + mCurrentUser
                                     + "; resetting USB host stack for MTP or PTP");
+                            // avoid leaking sensitive data from previous user
+                            mUsbDataUnlocked = false;
                             setEnabledFunctions(mCurrentFunctions, true);
                         }
                         mCurrentUser = msg.arg1;