Probing: Add support for exponential startup probing

webrtc/modules/pacing/paced_sender.cc

Index: webrtc/modules/pacing/paced_sender.cc
diff --git a/webrtc/modules/pacing/paced_sender.cc b/webrtc/modules/pacing/paced_sender.cc
index 2e5af7ab40b62fb66d02dc91e4324c33a744718f..23bfbb8dd25368c8e265833354e6368d5c2a307d 100644
--- a/webrtc/modules/pacing/paced_sender.cc
+++ b/webrtc/modules/pacing/paced_sender.cc
@@ -298,6 +298,7 @@ void PacedSender::SetEstimatedBitrate(int bitrate_bps) {
   pacing_bitrate_kbps_ =
       std::max(min_send_bitrate_kbps_, estimated_bitrate_bps_ / 1000) *
       kDefaultPaceMultiplier;
+  prober_->SetEstimatedBitrate(bitrate_bps);
 }
 
 void PacedSender::SetSendBitrateLimits(int min_send_bitrate_bps,
@@ -323,7 +324,7 @@ void PacedSender::InsertPacket(RtpPacketSender::Priority priority,
         << "SetEstimatedBitrate must be called before InsertPacket.";
 
   int64_t now_ms = clock_->TimeInMilliseconds();
-  prober_->OnIncomingPacket(bytes);
+  prober_->OnIncomingPacket(now_ms, bytes);
 
   if (capture_time_ms < 0)
     capture_time_ms = now_ms;
@@ -373,6 +374,11 @@ int64_t PacedSender::TimeUntilNextProcess() {
   return std::max<int64_t>(kMinPacketLimitMs - elapsed_time_ms, 0);
 }
 
+bool PacedSender::IsExpectingProbingResults() const {
+  CriticalSectionScoped cs(critsect_.get());
+  return prober_->IsExpectingProbingResults();
+}
+
 void PacedSender::Process() {
   int64_t now_us = clock_->TimeInMicroseconds();
   CriticalSectionScoped cs(critsect_.get());
@@ -458,7 +464,9 @@ bool PacedSender::SendPacket(const paced_sender::Packet& packet,
   critsect_->Enter();
 
   if (success) {
-    prober_->PacketSent(clock_->TimeInMilliseconds(), packet.bytes);
+    // Is this a probe ?
+    if (probe_cluster_id != PacketInfo::kNotAProbe)
+      prober_->PacketSent(clock_->TimeInMilliseconds(), packet.bytes);
     // TODO(holmer): High priority packets should only be accounted for if we
     // are allocating bandwidth for audio.
     if (packet.priority != kHighPriority) {
@@ -478,7 +486,9 @@ void PacedSender::SendPadding(size_t padding_needed, int probe_cluster_id) {
   critsect_->Enter();
 
   if (bytes_sent > 0) {
-    prober_->PacketSent(clock_->TimeInMilliseconds(), bytes_sent);
+    // Is this a probe ?
+    if (probe_cluster_id != PacketInfo::kNotAProbe)
+      prober_->PacketSent(clock_->TimeInMilliseconds(), bytes_sent);
     media_budget_->UseBudget(bytes_sent);
     padding_budget_->UseBudget(bytes_sent);
   }