Add context-aware "time" library wrapper.

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

+// 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

[iannucci, 2015/06/03 17:37:20]

systemtimer

[dnj, 2015/06/03 18:21:27]

(In "clock" package now).

+
+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)

[iannucci, 2015/06/03 17:37:20]

where does Timer come from? Should this be clock.Timer?

[dnj, 2015/06/03 18:21:27]

(In "clock" package now).

+
+func (t *systemTimer) GetC() (c <-chan time.Time) {

[iannucci, 2015/06/03 17:37:20]

C()

see https://golang.org/doc/effective_go.html#package-names

[dnj, 2015/06/03 18:21:27]

(In "clock" package now).

+        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()
+}