Improve bitrate probing for the audio-only case.

webrtc/modules/pacing/bitrate_prober_unittest.cc

Index: webrtc/modules/pacing/bitrate_prober_unittest.cc
diff --git a/webrtc/modules/pacing/bitrate_prober_unittest.cc b/webrtc/modules/pacing/bitrate_prober_unittest.cc
index 9ada11462572fda41178b0e05b0ecd2046ca2655..b5bc889014382e4581ca088a4ba9e86689ed5b02 100644
--- a/webrtc/modules/pacing/bitrate_prober_unittest.cc
+++ b/webrtc/modules/pacing/bitrate_prober_unittest.cc
@@ -88,10 +88,6 @@ TEST(BitrateProberTest, DoesntProbeWithoutRecentPackets) {
   // Let time pass, no large enough packets put into prober.
   now_ms += 6000;
   EXPECT_EQ(-1, prober.TimeUntilNextProbe(now_ms));
-  // Insert a small packet, not a candidate for probing.
-  prober.OnIncomingPacket(100);
-  EXPECT_FALSE(prober.IsProbing());
-  EXPECT_EQ(-1, prober.TimeUntilNextProbe(now_ms));
   // Insert a large-enough packet after downtime while probing should reset to
   // perform a new probe since the requested one didn't finish.
   prober.OnIncomingPacket(1000);
@@ -147,7 +143,7 @@ TEST(BitrateProberTest, ScaleBytesUsedForProbing) {
   prober.OnIncomingPacket(kPacketSizeBytes);
   int bytes_sent = 0;
   while (bytes_sent < kExpectedBytesSent) {
-    EXPECT_TRUE(prober.IsProbing());
+    ASSERT_TRUE(prober.IsProbing());
     prober.ProbeSent(0, kPacketSizeBytes);
     bytes_sent += kPacketSizeBytes;
   }