This class provides a default implementation of the IServiceProvider interface.
The IServiceProvider interface locates a service specified by its GUID and returns the interface pointer for the requested interface on the service. Class IServiceProviderImpl provides a default implementation of this interface.
IServiceProviderImpl specifies one method: QueryService, which creates or accesses the specified service and returns an interface pointer to the specified interface for the service.
The service map contains two entries: SERVICE_ENTRY, which indicates a specified service id (SID) supported by the object, and SERVICE_ENTRY_CHAIN, which calls QueryService to chain to another object.