Correction: The -expected.txt files are the same both with and without "virtual".

The only problem is this test times out:
virtual/webrtc-wpt-unified-plan/external/wpt/webrtc/RTCPeerConnection-setRemoteDescription-tracks.https.html

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/72b2a8b60167ba05092a5ce9fcfa0ae2d48d3280

commit 72b2a8b60167ba05092a5ce9fcfa0ae2d48d3280
Author: Henrik Boström <hbos@chromium.org>
Date: Thu Apr 12 14:33:36 2018

Running virtual external/wpt/webrtc/ with Unified Plan.

This adds RuntimeEnabled feature RTCUnifiedPlanByDefault (off by
default even in LayoutTests) which overrides the default SDP semantics
of RTCPeerConnection, and adds running external/wpt/webrtc/* as a
virtual test suite with this flag enabled.

The tests can be run as:
virtual/webrtc-wpt-unified-plan/external/wpt/webrtc/

The -expected.txt files are identical to the non-virtual versions.
The only problem introduced with Unified Plan is that the following
test times out:
virtual/webrtc-wpt-unified-plan/external/wpt/webrtc/
    RTCPeerConnection-setRemoteDescription-tracks.https.html
  Bug filed:  https://crbug.com/828866 

And unlike external/wpt/webrtc/
    RTCPeerConnection-setLocalDescription-answer.html,
virtual/webrtc-wpt-unified-plan/external/wpt/webrtc/
    RTCPeerConnection-setLocalDescription-answer.html
does not fail against the -expected.txt file.

Bug:  828793 ,  828866 
Change-Id: I51d86fc5a0388ae1d8bf5f8497f31795d205d5d2
Reviewed-on: https://chromium-review.googlesource.com/995278
Commit-Queue: Henrik Boström <hbos@chromium.org>
Reviewed-by: Harald Alvestrand <hta@chromium.org>
Reviewed-by: Philip Jägenstedt <foolip@chromium.org>
Cr-Commit-Position: refs/heads/master@{#550190}
[modify] https://crrev.com/72b2a8b60167ba05092a5ce9fcfa0ae2d48d3280/third_party/WebKit/LayoutTests/TestExpectations
[modify] https://crrev.com/72b2a8b60167ba05092a5ce9fcfa0ae2d48d3280/third_party/WebKit/LayoutTests/VirtualTestSuites
[add] https://crrev.com/72b2a8b60167ba05092a5ce9fcfa0ae2d48d3280/third_party/WebKit/LayoutTests/virtual/webrtc-wpt-unified-plan/external/wpt/webrtc/README.txt
[add] https://crrev.com/72b2a8b60167ba05092a5ce9fcfa0ae2d48d3280/third_party/WebKit/LayoutTests/virtual/webrtc-wpt-unified-plan/external/wpt/webrtc/RTCCertificate-expected.txt
[add] https://crrev.com/72b2a8b60167ba05092a5ce9fcfa0ae2d48d3280/third_party/WebKit/LayoutTests/virtual/webrtc-wpt-unified-plan/external/wpt/webrtc/RTCConfiguration-bundlePolicy-expected.txt
[add] https://crrev.com/72b2a8b60167ba05092a5ce9fcfa0ae2d48d3280/third_party/WebKit/LayoutTests/virtual/webrtc-wpt-unified-plan/external/wpt/webrtc/RTCConfiguration-iceServers-expected.txt
[add] https://crrev.com/72b2a8b60167ba05092a5ce9fcfa0ae2d48d3280/third_party/WebKit/LayoutTests/virtual/webrtc-wpt-unified-plan/external/wpt/webrtc/RTCPeerConnection-addTrack.https-expected.txt
[add] https://crrev.com/72b2a8b60167ba05092a5ce9fcfa0ae2d48d3280/third_party/WebKit/LayoutTests/virtual/webrtc-wpt-unified-plan/external/wpt/webrtc/RTCPeerConnection-createOffer-expected.txt
[add] https://crrev.com/72b2a8b60167ba05092a5ce9fcfa0ae2d48d3280/third_party/WebKit/LayoutTests/virtual/webrtc-wpt-unified-plan/external/wpt/webrtc/RTCPeerConnection-ontrack.https-expected.txt
[add] https://crrev.com/72b2a8b60167ba05092a5ce9fcfa0ae2d48d3280/third_party/WebKit/LayoutTests/virtual/webrtc-wpt-unified-plan/external/wpt/webrtc/RTCPeerConnection-setLocalDescription-answer-expected.txt
[add] https://crrev.com/72b2a8b60167ba05092a5ce9fcfa0ae2d48d3280/third_party/WebKit/LayoutTests/virtual/webrtc-wpt-unified-plan/external/wpt/webrtc/RTCPeerConnection-setRemoteDescription-replaceTrack.https-expected.txt
[modify] https://crrev.com/72b2a8b60167ba05092a5ce9fcfa0ae2d48d3280/third_party/blink/renderer/modules/peerconnection/rtc_peer_connection.cc
[modify] https://crrev.com/72b2a8b60167ba05092a5ce9fcfa0ae2d48d3280/third_party/blink/renderer/platform/runtime_enabled_features.json5

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/72b2a8b60167ba05092a5ce9fcfa0ae2d48d3280

commit 72b2a8b60167ba05092a5ce9fcfa0ae2d48d3280
Author: Henrik Boström <hbos@chromium.org>
Date: Thu Apr 12 14:33:36 2018

Running virtual external/wpt/webrtc/ with Unified Plan.

This adds RuntimeEnabled feature RTCUnifiedPlanByDefault (off by
default even in LayoutTests) which overrides the default SDP semantics
of RTCPeerConnection, and adds running external/wpt/webrtc/* as a
virtual test suite with this flag enabled.

The tests can be run as:
virtual/webrtc-wpt-unified-plan/external/wpt/webrtc/

The -expected.txt files are identical to the non-virtual versions.
The only problem introduced with Unified Plan is that the following
test times out:
virtual/webrtc-wpt-unified-plan/external/wpt/webrtc/
    RTCPeerConnection-setRemoteDescription-tracks.https.html
  Bug filed:  https://crbug.com/828866 

And unlike external/wpt/webrtc/
    RTCPeerConnection-setLocalDescription-answer.html,
virtual/webrtc-wpt-unified-plan/external/wpt/webrtc/
    RTCPeerConnection-setLocalDescription-answer.html
does not fail against the -expected.txt file.

Bug:  828793 ,  828866 
Change-Id: I51d86fc5a0388ae1d8bf5f8497f31795d205d5d2
Reviewed-on: https://chromium-review.googlesource.com/995278
Commit-Queue: Henrik Boström <hbos@chromium.org>
Reviewed-by: Harald Alvestrand <hta@chromium.org>
Reviewed-by: Philip Jägenstedt <foolip@chromium.org>
Cr-Commit-Position: refs/heads/master@{#550190}
[modify] https://crrev.com/72b2a8b60167ba05092a5ce9fcfa0ae2d48d3280/third_party/WebKit/LayoutTests/TestExpectations
[modify] https://crrev.com/72b2a8b60167ba05092a5ce9fcfa0ae2d48d3280/third_party/WebKit/LayoutTests/VirtualTestSuites
[add] https://crrev.com/72b2a8b60167ba05092a5ce9fcfa0ae2d48d3280/third_party/WebKit/LayoutTests/virtual/webrtc-wpt-unified-plan/external/wpt/webrtc/README.txt
[add] https://crrev.com/72b2a8b60167ba05092a5ce9fcfa0ae2d48d3280/third_party/WebKit/LayoutTests/virtual/webrtc-wpt-unified-plan/external/wpt/webrtc/RTCCertificate-expected.txt
[add] https://crrev.com/72b2a8b60167ba05092a5ce9fcfa0ae2d48d3280/third_party/WebKit/LayoutTests/virtual/webrtc-wpt-unified-plan/external/wpt/webrtc/RTCConfiguration-bundlePolicy-expected.txt
[add] https://crrev.com/72b2a8b60167ba05092a5ce9fcfa0ae2d48d3280/third_party/WebKit/LayoutTests/virtual/webrtc-wpt-unified-plan/external/wpt/webrtc/RTCConfiguration-iceServers-expected.txt
[add] https://crrev.com/72b2a8b60167ba05092a5ce9fcfa0ae2d48d3280/third_party/WebKit/LayoutTests/virtual/webrtc-wpt-unified-plan/external/wpt/webrtc/RTCPeerConnection-addTrack.https-expected.txt
[add] https://crrev.com/72b2a8b60167ba05092a5ce9fcfa0ae2d48d3280/third_party/WebKit/LayoutTests/virtual/webrtc-wpt-unified-plan/external/wpt/webrtc/RTCPeerConnection-createOffer-expected.txt
[add] https://crrev.com/72b2a8b60167ba05092a5ce9fcfa0ae2d48d3280/third_party/WebKit/LayoutTests/virtual/webrtc-wpt-unified-plan/external/wpt/webrtc/RTCPeerConnection-ontrack.https-expected.txt
[add] https://crrev.com/72b2a8b60167ba05092a5ce9fcfa0ae2d48d3280/third_party/WebKit/LayoutTests/virtual/webrtc-wpt-unified-plan/external/wpt/webrtc/RTCPeerConnection-setLocalDescription-answer-expected.txt
[add] https://crrev.com/72b2a8b60167ba05092a5ce9fcfa0ae2d48d3280/third_party/WebKit/LayoutTests/virtual/webrtc-wpt-unified-plan/external/wpt/webrtc/RTCPeerConnection-setRemoteDescription-replaceTrack.https-expected.txt
[modify] https://crrev.com/72b2a8b60167ba05092a5ce9fcfa0ae2d48d3280/third_party/blink/renderer/modules/peerconnection/rtc_peer_connection.cc
[modify] https://crrev.com/72b2a8b60167ba05092a5ce9fcfa0ae2d48d3280/third_party/blink/renderer/platform/runtime_enabled_features.json5

We've done plenty of progress here and forgotten about updating this bug. While there is more work to be done, the WPTs are not blocking launching Unified Plan. Closing this bug.