Bug 1669406 - add pref to blocklist codecs for WebRTC testing;r=dminor

Differential Revision: https://phabricator.services.mozilla.com/D92540

dom/media/webrtc/jsep/JsepSessionImpl.cpp

@@ -2096,6 +2096,24 @@ void JsepSessionImpl::SetupDefaultCodecs() {
   // codecs.  Note: only uses the video codecs.
   red->UpdateRedundantEncodings(mSupportedCodecs);
   mSupportedCodecs.push_back(std::move(red));
+
+  // Filter out codecs using pref (case sensitive), useful for testing.
+  nsCString filteredCodecsPref;
+  if (NS_OK ==
+      Preferences::GetCString("media.peerconnection.default_codecs.blocklist",
+                              filteredCodecsPref)) {
+    for (const auto& codecName : filteredCodecsPref.Split(',')) {
+      nsCString blocked(codecName.BeginReading(), codecName.Length());
+      blocked.StripWhitespace();
+      // Remove blocked codecs
+      mSupportedCodecs.erase(
+          std::remove_if(mSupportedCodecs.begin(), mSupportedCodecs.end(),
+                         [&](const UniquePtr<JsepCodecDescription>& codec) {
+                           return blocked.EqualsASCII(codec->mName.c_str());
+                         }),
+          mSupportedCodecs.end());
+    }
+  }
 }
 
 void JsepSessionImpl::SetupDefaultRtpExtensions() {