Change to calculate the real NTP in TimeTicks.

media/cast/cast_defines.h

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef MEDIA_CAST_CAST_DEFINES_H_
 #define MEDIA_CAST_CAST_DEFINES_H_
 
 #include <map>
 #include <set>
 
@@ skipping 40 matching lines @@
 // Each uint8 represents one cast frame.
 typedef std::map<uint8, PacketIdSet> MissingFramesAndPacketsMap;
 
 // TODO(pwestin): Re-factor the functions bellow into a class with static
 // methods.
 
 // Magic fractional unit. Used to convert time (in microseconds) to/from
 // fractional NTP seconds.
 static const double kMagicFractionalUnit = 4.294967296E3;
 
-// Network Time Protocol (NTP), which is in seconds relative to 0h UTC on
-// 1 January 1900.
-static const int64 kNtpEpochDeltaSeconds = GG_INT64_C(9435484800);
-static const int64 kNtpEpochDeltaMicroseconds =
-    kNtpEpochDeltaSeconds * base::Time::kMicrosecondsPerSecond;
-
 inline bool IsNewerFrameId(uint8 frame_id, uint8 prev_frame_id) {
   return (frame_id != prev_frame_id) &&
       static_cast<uint8>(frame_id - prev_frame_id) < 0x80;
 }
 
 inline bool IsOlderFrameId(uint8 frame_id, uint8 prev_frame_id) {
   return (frame_id == prev_frame_id) || IsNewerFrameId(prev_frame_id, frame_id);
 }
 
 inline bool IsNewerPacketId(uint16 packet_id, uint16 prev_packet_id) {
@@ skipping 26 matching lines @@
                                    uint32* fractions) {
   DCHECK_GE(time_us, 0) << "Time must NOT be negative";
   *seconds = static_cast<uint32>(time_us / base::Time::kMicrosecondsPerSecond);
   *fractions = static_cast<uint32>(
       (time_us % base::Time::kMicrosecondsPerSecond) * kMagicFractionalUnit);
 }
 
 inline void ConvertTimeToNtp(const base::TimeTicks& time,
                              uint32* ntp_seconds,
                              uint32* ntp_fractions) {
-  int64 time_us = time.ToInternalValue() - kNtpEpochDeltaMicroseconds;
+  int64 time_us = time.ToInternalValue();

[miu, 2013/10/23 18:24:02]

IMHO, it's much cleaner to work with only one timeline in the cast code. 
Meaning, I'd suggest you only convert to/from NTP time for the packets, but
otherwise have all other code be on the same timeline (i.e., same origin) as
base::TimeTicks::Now().

[pwestin, 2013/10/23 21:07:49]

Removed this function since it did not provide any value any longer

   ConvertTimeToFractions(time_us, ntp_seconds, ntp_fractions);
 }
 
 inline base::TimeTicks ConvertNtpToTime(uint32 ntp_seconds,
                                         uint32 ntp_fractions) {
   int64 ntp_time_us = static_cast<int64>(ntp_seconds) *
        base::Time::kMicrosecondsPerSecond;
   ntp_time_us += static_cast<int64>(ntp_fractions) / kMagicFractionalUnit;
-  return base::TimeTicks::FromInternalValue(ntp_time_us +
-      kNtpEpochDeltaMicroseconds);
+  return base::TimeTicks::FromInternalValue(ntp_time_us);
 }
 
 }  // namespace cast
 }  // namespace media
 
 #endif  // MEDIA_CAST_CAST_DEFINES_H_