This directory is for header files that are part of Native Client's
stable ABI, as exposed under Chromium by NaCl's IRT interfaces.  It
defines how PPAPI is exposed to user code as a NaCl IRT interface.  It
does not define PPAPI itself, whose stable ABI is defined by the
ppapi/c/ directory.

This directory only defines NaCl IRT interfaces that are specific to
Chromium's embedding of NaCl.  Non-PPAPI-specific NaCl IRT
interfaces are defined in native_client/src/untrusted/irt/irt.h.