// A simple thread abstraction that establishes a MessageLoop on a new thread.
// The consumer uses the MessageLoop of the thread to cause code to execute on
// the thread. When this object is destroyed the thread is terminated. All
// pending tasks queued on the thread's message loop will run to completion
// before the thread is terminated.
// This is a simple thread interface that backs to a native operating system
// thread. You should use this only when you want a thread that does not have
// an associated MessageLoop. Unittesting is the best example of this.
//
// The simplest interface to use is DelegateSimpleThread, which will create
// a new thread, and execute the Delegate's virtual Run() in this new thread
// until it has completed, exiting the thread.
//
// NOTE: You *MUST* call Join on the thread to clean up the underlying thread
// resources. You are also responsible for destructing the SimpleThread object.
// It is invalid to destroy a SimpleThread while it is running, or without
// Start() having been called (and a thread never created). The Delegate
// object should live as long as a DelegateSimpleThread.
//
// Thread Safety: A SimpleThread is not completely thread safe. It is safe to
// access it from the creating thread or from the newly created thread. This
// implies that the creator thread should be the thread that calls Join.
//
// Example:
// class MyThreadRunner : public DelegateSimpleThread::Delegate { ... };
// MyThreadRunner runner;
// DelegateSimpleThread thread(&runner, "good_name_here");
// thread.Start();
// // Start will return after the Thread has been successfully started and
// // initialized. The newly created thread will invoke runner->Run(), and
// // run until it returns.
// thread.Join(); // Wait until the thread has exited. You *MUST* Join!
// // The SimpleThread object is still valid, however you may not call Join
// // or Start again.
