Or do plugins like flash have the choice between native client and just using a shared library as they did and Pepper also supports that?
In the first case it would basically mean that flash would run sandboxed (and maybe on every system supported by Pepper, so once ARM support is added it could run there as well again). But probably with some speed-hit (~5% according to the documentation)
We use Pepper to sandbox some fully native plugins, where NaCl is not yet a good option due to things like codebase incompatibilities and startup performance. Two examples of this are the native PDF reader (on all platforms) and Flash on Chrome OS.
NaCL would probably have been mentioned if it was involved. I think Chrome can still do less fine-grained, OS-assisted sandboxing, and Flash on Pepper is cooperating with that.
Or do plugins like flash have the choice between native client and just using a shared library as they did and Pepper also supports that?
In the first case it would basically mean that flash would run sandboxed (and maybe on every system supported by Pepper, so once ARM support is added it could run there as well again). But probably with some speed-hit (~5% according to the documentation)