Change rtc::TimeNanos and rtc::TimeMicros return value from uint64_t to int64_t.

webrtc/api/stats/rtcstatsreport.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.
  */
 
@@ skipping 34 matching lines @@
     ConstIterator(const rtc::scoped_refptr<const RTCStatsReport>& report,
                   StatsMap::const_iterator it);
 
     // Reference report to make sure it is kept alive.
     rtc::scoped_refptr<const RTCStatsReport> report_;
     StatsMap::const_iterator it_;
   };
 
   // TODO(hbos): Remove "= 0" once Chromium unittest has been updated to call
   // with a parameter. crbug.com/627816
-  static rtc::scoped_refptr<RTCStatsReport> Create(uint64_t timestamp_us = 0);
+  static rtc::scoped_refptr<RTCStatsReport> Create(int64_t timestamp_us = 0);
 
-  explicit RTCStatsReport(uint64_t timestamp_us);
+  explicit RTCStatsReport(int64_t timestamp_us);
   RTCStatsReport(const RTCStatsReport& other) = delete;
 
-  uint64_t timestamp_us() const { return timestamp_us_; }
+  int64_t timestamp_us() const { return timestamp_us_; }
   bool AddStats(std::unique_ptr<const RTCStats> stats);
   const RTCStats* Get(const std::string& id) const;
   size_t size() const { return stats_.size(); }
 
   // Takes ownership of all the stats in |victim|, leaving it empty.
   void TakeMembersFrom(rtc::scoped_refptr<RTCStatsReport> victim);
 
   // Stats iterators. Stats are ordered lexicographically on |RTCStats::id|.
   ConstIterator begin() const;
   ConstIterator end() const;
@@ skipping 12 matching lines @@
 
   // Creates a human readable string representation of the report, listing all
   // of its stats objects.
   std::string ToString() const;
 
   friend class rtc::RefCountedObject<RTCStatsReport>;
 
  private:
   ~RTCStatsReport() override;
 
-  uint64_t timestamp_us_;
+  int64_t timestamp_us_;
   StatsMap stats_;
 };
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_API_STATS_RTCSTATSREPORT_H_