[WebRTC] Preparation CL for making Plan B throw an exception.

This CL adds the code that makes constructing an RTCPeerConnection with {sdpSemantics:"plan-b"} throw an exception, however it also adds a kill switch for this code path that is enabled by default (meaning we will not throw an exception). The kill switch will be made DISABLED_BY_DEFAULT in a follow-up CL so that in case we have to revert "making Plan B throw" we don't have to revert evertything this CL is adding, including a web platform test and a use counter that is likely to cause merge conflicts if reverted. Bug: chromium:857004 Change-Id: I8452b6d883ec71ba77cc59275b038ae2cac41c73 Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2949808 Reviewed-by: Harald Alvestrand <hta@chromium.org> Reviewed-by: Guido Urdaneta <guidou@chromium.org> Reviewed-by: Philip Jägenstedt <foolip@chromium.org> Commit-Queue: Henrik Boström <hbos@chromium.org> Cr-Commit-Position: refs/heads/master@{#891596}
web-platform-tests · Jun 11, 2021 · 66bea91 · 66bea91
1 parent 10b1658
commit 66bea91
Showing 1 changed file with 28 additions and 0 deletions.
diff --git a/webrtc/RTCPeerConnection-plan-b-is-not-supported.html b/webrtc/RTCPeerConnection-plan-b-is-not-supported.html
@@ -0,0 +1,28 @@
+<!doctype html>
+<meta charset=utf-8>
+<meta name="timeout" content="long">
+<title></title>
+<script src=/resources/testharness.js></script>
+<script src=/resources/testharnessreport.js></script>
+<script>
+'use strict';
+
+promise_test(async t => {
+  // Plan B is a legacy feature that should not be supported on a modern
+  // browser. To pass this test you must either ignore sdpSemantics altogether
+  // (and construct with Unified Plan despite us asking for Plan B) or throw an
+  // exception.
+  let pc = null;
+  try {
+    pc = new RTCPeerConnection({sdpSemantics:"plan-b"});
+    t.add_cleanup(() => pc.close());
+  } catch (e) {
+    // Test passed!
+    return;
+  }
+  // If we did not throw, we must not have gotten what we asked for. If
+  // sdpSemantics is not recognized by the browser it will be undefined here.
+  assert_not_equals(pc.getConfiguration().sdpSemantics, "plan-b");
+}, 'Plan B is not supported');
+
+</script>