I'll copy out this comment of mine in response to an analogous question: > Mozilla developers at the time actually have other plans with the Pepper plugin supp

I'll copy out this comment of mine in response to an analogous question: > Mozilla developers at the time actually have other plans with the Pepper plugin support: Adobe Flash (since that Chrome's Pepper Plugin API (PPAPI) is actually miles better and secure than the Netscape [-era - ed.] Plugin API or NPAPI). They abandoned Mortar (the name of the project) when Adobe have announced that it will retire Flash.