Now probe for x3 and x6 the initial start bitrate.

webrtc/modules/congestion_controller/probe_bitrate_estimator_unittest.cc

Index: webrtc/modules/congestion_controller/probe_bitrate_estimator_unittest.cc
diff --git a/webrtc/modules/congestion_controller/probe_bitrate_estimator_unittest.cc b/webrtc/modules/congestion_controller/probe_bitrate_estimator_unittest.cc
index 0c143b5efd8c1166f516468d5fc21b958c0c3600..e4ec739e18dfaf9157df7b0e666afa71c505a4cc 100644
--- a/webrtc/modules/congestion_controller/probe_bitrate_estimator_unittest.cc
+++ b/webrtc/modules/congestion_controller/probe_bitrate_estimator_unittest.cc
@@ -60,9 +60,9 @@ TEST_F(TestProbeBitrateEstimator, FastReceive) {
 
 TEST_F(TestProbeBitrateEstimator, TooFastReceive) {
   AddPacketFeedback(0, 1000, 0, 19);
-  AddPacketFeedback(0, 1000, 10, 30);
-  AddPacketFeedback(0, 1000, 20, 40);
-  AddPacketFeedback(0, 1000, 40, 50);
+  AddPacketFeedback(0, 1000, 10, 22);
+  AddPacketFeedback(0, 1000, 20, 25);
+  AddPacketFeedback(0, 1000, 40, 27);
 
   EXPECT_EQ(measured_bps_, INVALID_BPS);
 }