The idea is that, with the right flag settings, this will cause the OS to
terminate remaining viewer child processes when the viewer terminates --
whether or not it terminates intentionally. Of course, if LLProcess's caller
specifies autokill=false, e.g. to run the viewer updater, that asserts that we
WANT the child to persist beyond the viewer session itself.
LLProcessLauncher had the somewhat fuzzy mandate of (1) accumulating
parameters with which to launch a child process and (2) sometimes tracking the
lifespan of the ensuing child process. But a valid LLProcessLauncher object
might or might not have ever been associated with an actual child process.
LLProcess specifically tracks a child process. In effect, it's a fairly thin
wrapper around a process HANDLE (on Windows) or pid_t (elsewhere), with
lifespan management thrown in. A static LLProcess::create() method launches a
new child; create() accepts an LLSD bundle with child parameters. So building
up a parameter bundle is deferred to LLSD rather than conflated with the
process management object.
Reconcile all known LLProcessLauncher consumers in the viewer code base,
notably the class unit tests.
Nat Goodspeed