Comment 3 for bug 1260103

> I would modify base::GetShmemTempDir() to lookup a path via
> base::PathService and then have Oxide override this.

GetShmemTempDir() tries to create a temp file under /dev/shm/, so the problem is not the path itself, it’s the name of the temp file under that path.
IIUC what needs to be modified is the TempFileName() function, to return something like "snap.${SNAP_NAME}.XXXXXX", if SNAP_NAME is defined, and fall back to the default value, ".org.chromium.Chromium.XXXXXX".