type sync.Locker

5 uses

	sync (current package)
		cond.go#L25: 	L Locker
		cond.go#L32: func NewCond(l Locker) *Cond {
		mutex.go#L31: type Locker interface {
		rwmutex.go#L157: func (rw *RWMutex) RLocker() Locker {

	net/http
		transport.go#L2520: 	testHookMu                     sync.Locker = fakeLocker{} // guards following