Change default timestamp to 64 bits in all webrtc directories.

BUG=
R=pbos@webrtc.org, pthatcher@webrtc.org, solenberg@webrtc.org

Review URL: https://codereview.webrtc.org/1835053002 .

Cr-Commit-Position: refs/heads/master@{#12646}
diff --git a/webrtc/base/asyncudpsocket.cc b/webrtc/base/asyncudpsocket.cc
index 7eb2a0e..fc7d887 100644
--- a/webrtc/base/asyncudpsocket.cc
+++ b/webrtc/base/asyncudpsocket.cc
@@ -59,7 +59,7 @@
 
 int AsyncUDPSocket::Send(const void *pv, size_t cb,
                          const rtc::PacketOptions& options) {
-  rtc::SentPacket sent_packet(options.packet_id, rtc::Time());
+  rtc::SentPacket sent_packet(options.packet_id, rtc::TimeMillis());
   int ret = socket_->Send(pv, cb);
   SignalSentPacket(this, sent_packet);
   return ret;
@@ -68,7 +68,7 @@
 int AsyncUDPSocket::SendTo(const void *pv, size_t cb,
                            const SocketAddress& addr,
                            const rtc::PacketOptions& options) {
-  rtc::SentPacket sent_packet(options.packet_id, rtc::Time());
+  rtc::SentPacket sent_packet(options.packet_id, rtc::TimeMillis());
   int ret = socket_->SendTo(pv, cb, addr);
   SignalSentPacket(this, sent_packet);
   return ret;