Only use BBRs pacer if the unit test is running BBR.

webrtc/modules/remote_bitrate_estimator/test/packet_sender.cc

Index: webrtc/modules/remote_bitrate_estimator/test/packet_sender.cc
diff --git a/webrtc/modules/remote_bitrate_estimator/test/packet_sender.cc b/webrtc/modules/remote_bitrate_estimator/test/packet_sender.cc
index 33209cab267debfaa9f4033fa1ce3139d52a533e..1eed3809d758455ea86346c210c1695afdc26ff6 100644
--- a/webrtc/modules/remote_bitrate_estimator/test/packet_sender.cc
+++ b/webrtc/modules/remote_bitrate_estimator/test/packet_sender.cc
@@ -159,9 +159,10 @@ PacedVideoSender::PacedVideoSender(PacketProcessorListener* listener,
                                    VideoSource* source,
                                    BandwidthEstimatorType estimator)
     : VideoSender(listener, source, estimator),
-      // Ugly hack to use BBR's pacer.
-      // TODO(gnish): Make pacer choice dependant on the algorithm being used.
-      pacer_(new BbrPacedSender(&clock_, this, nullptr)) {
+      pacer_(
+          estimator == kBbrEstimator
+              ? static_cast<Pacer*>(new BbrPacedSender(&clock_, this, nullptr))
+              : static_cast<Pacer*>(new PacedSender(&clock_, this, nullptr))) {
   modules_.push_back(pacer_.get());
   pacer_->SetEstimatedBitrate(source->bits_per_second());
 }