Aha, I see it's a shared object. It's sandboxed, though, so quite similar to NaCl.

Both NaCl and the plugins are running native code. NaCl is not PNaCl.

So it's using the NaCl sandbox and interface without the bytecode parts?

As I understand it, NaCl is a Pepper plugin, but Pepper does not rely on NaCl. Other Pepper plugins are not necessarily using NaCl.

https://code.google.com/p/nativeclient/wiki/Pepper