RTCStatsCollector: timestamps updated.

webrtc/stats/rtcstatscollector.h

 /*
  *  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_STATS_RTCSTATSCOLLECTOR_H_
 #define WEBRTC_STATS_RTCSTATSCOLLECTOR_H_
 
 #include <memory>
 
 #include "webrtc/api/rtcstats_objects.h"
 #include "webrtc/api/rtcstatsreport.h"
 #include "webrtc/base/scoped_ref_ptr.h"
-#include "webrtc/base/timing.h"
+#include "webrtc/base/timeutils.h"
 
 namespace webrtc {
 
 class PeerConnection;
 
 // All calls to the collector and gathering of stats is performed on the
 // signaling thread. A stats report is cached for |cache_lifetime_| ms.
 class RTCStatsCollector {
  public:
   explicit RTCStatsCollector(
       PeerConnection* pc,
-      double cache_lifetime = 0.05,
-      std::unique_ptr<rtc::Timing> timing = std::unique_ptr<rtc::Timing>(
-          new rtc::Timing()));
+      int64_t cache_lifetime_us = 50 * rtc::kNumMicrosecsPerMillisec);
 
   // Gets a recent stats report. If there is a report cached that is still fresh
   // it is returned, otherwise new stats are gathered and returned. A report is
   // considered fresh for |cache_lifetime_| ms. const RTCStatsReports are safe
   // to use across multiple threads and may be destructed on any thread.
   rtc::scoped_refptr<const RTCStatsReport> GetStatsReport();
   // Clears the cache's reference to the most recent stats report. Subsequently
   // calling |GetStatsReport| guarantees fresh stats.
   void ClearCachedStatsReport();
 
  private:
   bool IsOnSignalingThread() const;
 
-  std::unique_ptr<RTCPeerConnectionStats> ProducePeerConnectionStats() const;
+  std::unique_ptr<RTCPeerConnectionStats> ProducePeerConnectionStats(
+      int64_t timestamp_us) const;
 
   PeerConnection* const pc_;
-  mutable std::unique_ptr<rtc::Timing> timing_;
-  // Time relative to the UNIX epoch (Jan 1, 1970, UTC), in seconds.
-  double cache_timestamp_;
-  double cache_lifetime_;  // In seconds.
+  // A timestamp, in microseconds, that is based on a timer that is
+  // monotonically increasing. That is, even if the system clock is modified the
+  // difference between the timer and this timestamp is how fresh the cached
+  // report is.
+  int64_t cache_timestamp_us_;
+  int64_t cache_lifetime_us_;
   rtc::scoped_refptr<const RTCStatsReport> cached_report_;
 };
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_STATS_RTCSTATSCOLLECTOR_H_