Adding the ability to use a simulated clock for unit tests.

webrtc/base/simulatedclock.h

Index: webrtc/base/simulatedclock.h
diff --git a/webrtc/base/simulatedclock.h b/webrtc/base/simulatedclock.h
new file mode 100644
index 0000000000000000000000000000000000000000..6af65df3eda08899b2b72d43602e07d8bbf35947
--- /dev/null
+++ b/webrtc/base/simulatedclock.h
@@ -0,0 +1,48 @@
+/*
+ *  Copyright 2016 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#ifndef WEBRTC_BASE_SIMULATEDCLOCK_H_
+#define WEBRTC_BASE_SIMULATEDCLOCK_H_
+
+#include "webrtc/base/criticalsection.h"
+#include "webrtc/base/timeutils.h"
+
+namespace rtc {
+
+// Simulated clock for use with unit tests, which does not tick on its own.
+// Starts at time 0.
+class SimulatedClock : public ClockInterface {

[juberti2, 2016/04/25 20:18:23]

Should this be FakeClock, to match our other fakes?

[Taylor Brandstetter, 2016/04/26 01:22:32]

Done.

+ public:
+  ~SimulatedClock() override {}
+
+  // ClockInterface implementation.
+  uint64_t TimeNanos() const override;
+
+  // Methods that can be used by the test to control the time.
+
+  // Should only be used to set a time in the future.
+  void SetTimeNanos(uint64_t nanos);
+
+  void AdvanceTimeNanos(uint64_t nanos);
+
+  void AdvanceTimeMicros(uint64_t micros);
+
+  void AdvanceTimeMillis(uint64_t millis);
+
+  void AdvanceTimeSeconds(uint64_t seconds);
+
+ private:
+  CriticalSection lock_;
+  uint64_t time_ GUARDED_BY(lock_) = 0u;
+};
+
+}  // namespace rtc
+
+#endif  // WEBRTC_BASE_SIMULATEDCLOCK_H_