External Mojo service support

This directory contains utilities to ease development of Mojo services that run in processes outside of Chromium/cast_shell. The simplest model is to create a subclass of ‘ServiceProcess’ (and implement ‘ServiceProcess::Create()’ that returns an instance of that subclass), and link with ‘standalone_service_main’ to create the executable. In your ‘ServiceProcess’ implementation, you can bind to Mojo interfaces using the provided ‘Connector’ pointer, and/or register your own Mojo services for use by other processes.

The ‘ChromiumServiceWrapper’ class is intended to allow Mojo services that were intended to be embedded into cast_shell (or other ServiceManager embedder) to be moved into a completely separate process. It forwards ‘BindInterface()’ calls to the ‘service_manager::Service’ API. You can use ‘CreateChromiumServiceRequest()’ to create a ‘service_manager::ServiceRequest’ to emulate the normal service creation flow; the ‘service_manager::Service::OnStart()’ method will be called automatically.

The ‘standalone_mojo_broker’ is intended for use on platforms where there is no cast_shell running; this allows Mojo services outside of cast_shell to communicate with each other without any Chromium embedder on the system.