Refactor how padding is calculated.

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 167be23ab624fda0c7338203dfe9fffb94218257..4a7497a64b1e82c97ef89e051a8b4750fd0b6e80 100644
--- a/webrtc/modules/pacing/paced_sender.cc
+++ b/webrtc/modules/pacing/paced_sender.cc
@@ -245,8 +245,7 @@ class IntervalBudget {
 const int64_t PacedSender::kMaxQueueLengthMs = 2000;
 const float PacedSender::kDefaultPaceMultiplier = 2.5f;
 
-PacedSender::PacedSender(Clock* clock,
-                         PacketSender* packet_sender)
+PacedSender::PacedSender(Clock* clock, PacketSender* packet_sender)
     : clock_(clock),
       packet_sender_(packet_sender),
       critsect_(CriticalSectionWrapper::CreateCriticalSection()),
@@ -257,6 +256,7 @@ PacedSender::PacedSender(Clock* clock,
       prober_(new BitrateProber()),
       estimated_bitrate_bps_(0),
       min_send_bitrate_kbps_(0u),
+      max_padding_bitrate_kbps_(0u),
       pacing_bitrate_kbps_(0),
       time_last_update_us_(clock->TimeInMicroseconds()),
       packets_(new paced_sender::PacketQueue(clock)),
@@ -296,7 +296,7 @@ void PacedSender::SetAllocatedSendBitrate(int allocated_bitrate,
   pacing_bitrate_kbps_ =
       std::max(min_send_bitrate_kbps_, estimated_bitrate_bps_ / 1000) *
       kDefaultPaceMultiplier;
-  padding_budget_->set_target_rate_kbps(padding_bitrate / 1000);
+  max_padding_bitrate_kbps_ = padding_bitrate / 1000;
 }
 
 void PacedSender::InsertPacket(RtpPacketSender::Priority priority,
@@ -368,6 +368,8 @@ void PacedSender::Process() {
   int64_t elapsed_time_ms = (now_us - time_last_update_us_ + 500) / 1000;
   time_last_update_us_ = now_us;
   int target_bitrate_kbps = pacing_bitrate_kbps_;
+  padding_budget_->set_target_rate_kbps(
+      std::min(estimated_bitrate_bps_ / 1000, max_padding_bitrate_kbps_));
   // TODO(holmer): Remove the !paused_ check when issue 5307 has been fixed.
   if (!paused_ && elapsed_time_ms > 0) {
     size_t queue_size_bytes = packets_->SizeInBytes();
@@ -416,15 +418,16 @@ void PacedSender::Process() {
   if (paused_ || !packets_->Empty())
     return;
 
-  size_t padding_needed;
-  if (prober_->IsProbing()) {
-    padding_needed = prober_->RecommendedPacketSize();
-  } else {
-    padding_needed = padding_budget_->bytes_remaining();
-  }
+  // We can not send padding unless a normal packet has first been sent. If we
+  // do, time stamps gets messed up.
+  if (packet_counter_ > 0) {
+    size_t padding_needed = prober_->IsProbing()
+                                ? prober_->RecommendedPacketSize()
+                                : padding_budget_->bytes_remaining();
 
-  if (padding_needed > 0)
-    SendPadding(static_cast<size_t>(padding_needed));
+    if (padding_needed > 0)
+      SendPadding(static_cast<size_t>(padding_needed));
+  }
 }
 
 bool PacedSender::SendPacket(const paced_sender::Packet& packet,