Add tsan suppressions in advance of landing WebRTC refactoring

Bug: webrtc:9012
Change-Id: Ib83fa7046c2e7517e0051e0fdb433487ad636ceb
Reviewed-on: https://chromium-review.googlesource.com/962784Reviewed-by: Alexander Potapenko <glider@chromium.org>
Commit-Queue: Alexander Potapenko <glider@chromium.org>
Cr-Commit-Position: refs/heads/master@{#543336}

build/sanitizers/tsan_suppressions.cc

@@ -78,6 +78,9 @@ char kTSanDefaultSuppressions[] =
     "race:webrtc::RTPSender::ProcessBitrate\n"
     "race:webrtc::VideoCodingModuleImpl::Decode\n"
     "race:webrtc::RTPSender::SendOutgoingData\n"
+    "race:webrtc::LibvpxVp8Encoder::GetEncodedPartitions\n"
+    "race:webrtc::LibvpxVp8Encoder::Encode\n"
+    // TODO(sprang): Remove VP8EncoderImpl suppressions after fixing webrtc:9012
     "race:webrtc::VP8EncoderImpl::GetEncodedPartitions\n"
     "race:webrtc::VP8EncoderImpl::Encode\n"
     "race:webrtc::ViEEncoder::DeliverFrame\n"