Reland "Rewrite WebRtcSession BUNDLE tests as PeerConnection tests"

This is a reland of b49b66109ea8a0a33a3192ebccf91366af2e49ae.

Original change's description:
> Rewrite WebRtcSession BUNDLE tests as PeerConnection tests
> 
> Bug: webrtc:8222
> Change-Id: Id47e4544dc073564ad7e63d02865ca80dd5a85ff
> Reviewed-on: https://webrtc-review.googlesource.com/8280
> Commit-Queue: Steve Anton <steveanton@webrtc.org>
> Reviewed-by: Taylor Brandstetter <deadbeef@webrtc.org>
> Cr-Commit-Position: refs/heads/master@{#20365}

Bug: webrtc:8222
Change-Id: If3dcd8090875c641881e2b9e92fc1db387ba1de5
Reviewed-on: https://webrtc-review.googlesource.com/14400
Commit-Queue: Steve Anton <steveanton@webrtc.org>
Reviewed-by: Taylor Brandstetter <deadbeef@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#20397}
diff --git a/pc/BUILD.gn b/pc/BUILD.gn
index 02a8e9a..3e552c9 100644
--- a/pc/BUILD.gn
+++ b/pc/BUILD.gn
@@ -391,6 +391,7 @@
       "localaudiosource_unittest.cc",
       "mediaconstraintsinterface_unittest.cc",
       "mediastream_unittest.cc",
+      "peerconnection_bundle_unittest.cc",
       "peerconnection_crypto_unittest.cc",
       "peerconnection_ice_unittest.cc",
       "peerconnection_integrationtest.cc",