Remove libs/clock in favor of luci-go/common/clock.

go/src/infra/libs/clock/systemtimer.go

Index: go/src/infra/libs/clock/systemtimer.go
diff --git a/go/src/infra/libs/clock/systemtimer.go b/go/src/infra/libs/clock/systemtimer.go
deleted file mode 100644
index 84b31dc5e8eba1efcff76df918d2147c0477ada0..0000000000000000000000000000000000000000
--- a/go/src/infra/libs/clock/systemtimer.go
+++ /dev/null
@@ -1,38 +0,0 @@
-// Copyright 2015 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-package clock
-
-import (
-	"time"
-)
-
-// A Timer implementation that uses time.Timer.
-type systemTimer struct {
-	T *time.Timer // The underlying timer. Starts as nil, is initialized on Reset.
-}
-
-var _ Timer = (*systemTimer)(nil)
-
-func (t *systemTimer) GetC() (c <-chan time.Time) {
-	if t.T != nil {
-		c = t.T.C
-	}
-	return
-}
-
-func (t *systemTimer) Reset(d time.Duration) bool {
-	if t.T == nil {
-		t.T = time.NewTimer(d)
-		return false
-	}
-	return t.T.Reset(d)
-}
-
-func (t *systemTimer) Stop() bool {
-	if t.T == nil {
-		return false
-	}
-	return t.T.Stop()
-}