Fix flake in AddMediaToConnectedBundleDoesNotRestartIce test

EXPECT_EQ(0u, caller()->ice_connection_state_history().size());

Was failing since it cleared the connection state history before
the caller had finished transitioning to Completed, so the initial
transitions would be mistaken for later transitions.

Bug: None
Change-Id: I7043638f077ac5dcaeeca0d3ea6accc93c920364
Reviewed-on: https://webrtc-review.googlesource.com/16261
Reviewed-by: Peter Thatcher <pthatcher@webrtc.org>
Commit-Queue: Peter Thatcher <pthatcher@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#20570}
diff --git a/pc/peerconnection_integrationtest.cc b/pc/peerconnection_integrationtest.cc
index c10186a..6184241 100644
--- a/pc/peerconnection_integrationtest.cc
+++ b/pc/peerconnection_integrationtest.cc
@@ -3124,6 +3124,8 @@
   caller()->AddAudioOnlyMediaStream();
   caller()->CreateAndSetAndSignalOffer();
   ASSERT_TRUE_WAIT(SignalingStateStable(), kDefaultTimeout);
+  ASSERT_EQ_WAIT(PeerConnectionInterface::kIceConnectionCompleted,
+                 caller()->ice_connection_state(), kDefaultTimeout);
 
   caller()->clear_ice_connection_state_history();