replace NtpTime->Clock with Clock->NtpTime dependency

webrtc/system_wrappers/include/ntp_time.h

 /*
 *  Copyright (c) 2015 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_SYSTEM_WRAPPERS_INCLUDE_NTP_TIME_H_
 #define WEBRTC_SYSTEM_WRAPPERS_INCLUDE_NTP_TIME_H_
 
 #include <stdint.h>
 
-#include "webrtc/system_wrappers/include/clock.h"
-
 namespace webrtc {
 
 class NtpTime {
  public:
   NtpTime() : seconds_(0), fractions_(0) {}
-  explicit NtpTime(const Clock& clock) {
-    clock.CurrentNtp(seconds_, fractions_);
-  }
   NtpTime(uint32_t seconds, uint32_t fractions)
       : seconds_(seconds), fractions_(fractions) {}
 
   NtpTime(const NtpTime&) = default;
   NtpTime& operator=(const NtpTime&) = default;
 
-  void SetCurrent(const Clock& clock) {
-    clock.CurrentNtp(seconds_, fractions_);
-  }
   void Set(uint32_t seconds, uint32_t fractions) {
     seconds_ = seconds;
     fractions_ = fractions;
   }
   void Reset() {
     seconds_ = 0;
     fractions_ = 0;
   }
 
-  int64_t ToMs() const { return Clock::NtpToMs(seconds_, fractions_); }
-
+  int64_t ToMs() const {
+    static constexpr double kNtpFracPerMs = 4.294967296E6;  // 2^32 / 1000.
+    const double frac_ms = static_cast<double>(fractions_) / kNtpFracPerMs;
+    return 1000 * static_cast<int64_t>(seconds_) +
+           static_cast<int64_t>(frac_ms + 0.5);
+  }
   // NTP standard (RFC1305, section 3.1) explicitly state value 0/0 is invalid.
   bool Valid() const { return !(seconds_ == 0 && fractions_ == 0); }
 
   uint32_t seconds() const { return seconds_; }
   uint32_t fractions() const { return fractions_; }
 
  private:
   uint32_t seconds_;
   uint32_t fractions_;
 };
 
 inline bool operator==(const NtpTime& n1, const NtpTime& n2) {
   return n1.seconds() == n2.seconds() && n1.fractions() == n2.fractions();
 }
 inline bool operator!=(const NtpTime& n1, const NtpTime& n2) {
   return !(n1 == n2);
 }
 
 }  // namespace webrtc
 #endif  // WEBRTC_SYSTEM_WRAPPERS_INCLUDE_NTP_TIME_H_