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1 // Copyright 2014 The Chromium Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4 
5 #ifndef CAST_MEDIA_TEST_SKEWED_TICK_CLOCK_H
6 #define CAST_MEDIA_TEST_SKEWED_TICK_CLOCK_H
7 
8 #include "base/time/tick_clock.h"
9 #include "base/time/time.h"
10 
11 namespace media {
12 namespace cast {
13 namespace test {
14 
15 // Wraps a base::TickClock, and lets you change the speed and offset
16 // of time compared to the wrapped clock. See SetSkew for how usage.
17 class SkewedTickClock : public base::TickClock {
18  public:
19   // Does not take ownership of |clock_|.
20   explicit SkewedTickClock(base::TickClock* clock_);
21   // |skew| > 1.0 means clock runs faster.
22   // |offset| > 0 means clock returns times from the future.
23   // Note, |offset| is cumulative.
24   // Also note that changing the skew will never make the clock
25   // jump forwards or backwards, only changing the offset will
26   // do that.
27   void SetSkew(double skew, base::TimeDelta offset);
28   virtual base::TimeTicks NowTicks() OVERRIDE;
29 
30  private:
31   base::TimeTicks SkewTicks(base::TimeTicks now);
32   base::TickClock* clock_;  // Not owned.
33   double skew_;
34   base::TimeTicks last_skew_set_time_;
35   base::TimeTicks skew_clock_at_last_set_;
36 
37   DISALLOW_COPY_AND_ASSIGN(SkewedTickClock);
38 };
39 
40 }  // namespace test
41 }  // namespace cast
42 }  // namespace media
43 
44 #endif  // CAST_MEDIA_TEST_SKEWED_TICK_CLOCK_H
45