type sync.Locker

5 uses

	sync (current package)
		cond.go#L41: 	L Locker
		cond.go#L48: func NewCond(l Locker) *Cond {
		mutex.go#L37: type Locker interface {
		rwmutex.go#L240: func (rw *RWMutex) RLocker() Locker {

	net/http
		transport.go#L2736: 	testHookMu                     sync.Locker = fakeLocker{} // guards following