diff --git a/pc/rtc_stats_collector.cc b/pc/rtc_stats_collector.cc
index e1527d5..53b970c 100644
--- a/pc/rtc_stats_collector.cc
+++ b/pc/rtc_stats_collector.cc
@@ -1040,7 +1040,7 @@
     // Prepare |transceiver_stats_infos_| for use in
     // |ProducePartialResultsOnNetworkThread| and
     // |ProducePartialResultsOnSignalingThread|.
-    transceiver_stats_infos_ = PrepareTransceiverStatsInfos_s();
+    transceiver_stats_infos_ = PrepareTransceiverStatsInfos_s_w();
     // Prepare |transport_names_| for use in
     // |ProducePartialResultsOnNetworkThread|.
     transport_names_ = PrepareTransportNames_s();
@@ -1049,6 +1049,10 @@
     // thread.
     // TODO(holmer): To avoid the hop we could move BWE and BWE stats to the
     // network thread, where it more naturally belongs.
+    // TODO(https://crbug.com/webrtc/11767): In the meantime we can piggyback on
+    // the blocking-invoke that is already performed in
+    // PrepareTransceiverStatsInfos_s_w() so that we can call GetCallStats()
+    // without additional blocking-invokes.
     call_stats_ = pc_->GetCallStats();
 
     // Don't touch |network_report_| on the signaling thread until
@@ -1078,6 +1082,8 @@
 void RTCStatsCollector::ProducePartialResultsOnSignalingThread(
     int64_t timestamp_us) {
   RTC_DCHECK(signaling_thread_->IsCurrent());
+  rtc::Thread::ScopedDisallowBlockingCalls no_blocking_calls;
+
   partial_report_ = RTCStatsReport::Create(timestamp_us);
 
   ProducePartialResultsOnSignalingThreadImpl(timestamp_us,
@@ -1095,6 +1101,8 @@
     int64_t timestamp_us,
     RTCStatsReport* partial_report) {
   RTC_DCHECK(signaling_thread_->IsCurrent());
+  rtc::Thread::ScopedDisallowBlockingCalls no_blocking_calls;
+
   ProduceDataChannelStats_s(timestamp_us, partial_report);
   ProduceMediaStreamStats_s(timestamp_us, partial_report);
   ProduceMediaStreamTrackStats_s(timestamp_us, partial_report);
@@ -1105,6 +1113,8 @@
 void RTCStatsCollector::ProducePartialResultsOnNetworkThread(
     int64_t timestamp_us) {
   RTC_DCHECK(network_thread_->IsCurrent());
+  rtc::Thread::ScopedDisallowBlockingCalls no_blocking_calls;
+
   // Touching |network_report_| on this thread is safe by this method because
   // |network_report_event_| is reset before this method is invoked.
   network_report_ = RTCStatsReport::Create(timestamp_us);
@@ -1132,6 +1142,8 @@
     const std::map<std::string, CertificateStatsPair>& transport_cert_stats,
     RTCStatsReport* partial_report) {
   RTC_DCHECK(network_thread_->IsCurrent());
+  rtc::Thread::ScopedDisallowBlockingCalls no_blocking_calls;
+
   ProduceCertificateStats_n(timestamp_us, transport_cert_stats, partial_report);
   ProduceCodecStats_n(timestamp_us, transceiver_stats_infos_, partial_report);
   ProduceIceCandidateAndPairStats_n(timestamp_us, transport_stats_by_name,
@@ -1218,6 +1230,8 @@
     const std::map<std::string, CertificateStatsPair>& transport_cert_stats,
     RTCStatsReport* report) const {
   RTC_DCHECK(network_thread_->IsCurrent());
+  rtc::Thread::ScopedDisallowBlockingCalls no_blocking_calls;
+
   for (const auto& transport_cert_stats_pair : transport_cert_stats) {
     if (transport_cert_stats_pair.second.local) {
       ProduceCertificateStatsFromSSLCertificateStats(
@@ -1235,6 +1249,8 @@
     const std::vector<RtpTransceiverStatsInfo>& transceiver_stats_infos,
     RTCStatsReport* report) const {
   RTC_DCHECK(network_thread_->IsCurrent());
+  rtc::Thread::ScopedDisallowBlockingCalls no_blocking_calls;
+
   for (const auto& stats : transceiver_stats_infos) {
     if (!stats.mid) {
       continue;
@@ -1276,6 +1292,8 @@
     int64_t timestamp_us,
     RTCStatsReport* report) const {
   RTC_DCHECK_RUN_ON(signaling_thread_);
+  rtc::Thread::ScopedDisallowBlockingCalls no_blocking_calls;
+
   std::vector<DataChannel::Stats> data_stats = pc_->GetDataChannelStats();
   for (const auto& stats : data_stats) {
     std::unique_ptr<RTCDataChannelStats> data_channel_stats(
@@ -1301,6 +1319,8 @@
     const Call::Stats& call_stats,
     RTCStatsReport* report) const {
   RTC_DCHECK(network_thread_->IsCurrent());
+  rtc::Thread::ScopedDisallowBlockingCalls no_blocking_calls;
+
   for (const auto& entry : transport_stats_by_name) {
     const std::string& transport_name = entry.first;
     const cricket::TransportStats& transport_stats = entry.second;
@@ -1381,6 +1401,7 @@
     int64_t timestamp_us,
     RTCStatsReport* report) const {
   RTC_DCHECK(signaling_thread_->IsCurrent());
+  rtc::Thread::ScopedDisallowBlockingCalls no_blocking_calls;
 
   std::map<std::string, std::vector<std::string>> track_ids;
 
@@ -1417,6 +1438,8 @@
     int64_t timestamp_us,
     RTCStatsReport* report) const {
   RTC_DCHECK(signaling_thread_->IsCurrent());
+  rtc::Thread::ScopedDisallowBlockingCalls no_blocking_calls;
+
   for (const RtpTransceiverStatsInfo& stats : transceiver_stats_infos_) {
     std::vector<rtc::scoped_refptr<RtpSenderInternal>> senders;
     for (const auto& sender : stats.transceiver->senders()) {
@@ -1438,6 +1461,8 @@
     int64_t timestamp_us,
     RTCStatsReport* report) const {
   RTC_DCHECK(signaling_thread_->IsCurrent());
+  rtc::Thread::ScopedDisallowBlockingCalls no_blocking_calls;
+
   for (const RtpTransceiverStatsInfo& transceiver_stats_info :
        transceiver_stats_infos_) {
     const auto& track_media_info_map =
@@ -1519,6 +1544,8 @@
     int64_t timestamp_us,
     RTCStatsReport* report) const {
   RTC_DCHECK(signaling_thread_->IsCurrent());
+  rtc::Thread::ScopedDisallowBlockingCalls no_blocking_calls;
+
   std::unique_ptr<RTCPeerConnectionStats> stats(
       new RTCPeerConnectionStats("RTCPeerConnection", timestamp_us));
   stats->data_channels_opened = internal_record_.data_channels_opened;
@@ -1531,6 +1558,7 @@
     const std::vector<RtpTransceiverStatsInfo>& transceiver_stats_infos,
     RTCStatsReport* report) const {
   RTC_DCHECK(network_thread_->IsCurrent());
+  rtc::Thread::ScopedDisallowBlockingCalls no_blocking_calls;
 
   for (const RtpTransceiverStatsInfo& stats : transceiver_stats_infos) {
     if (stats.media_type == cricket::MEDIA_TYPE_AUDIO) {
@@ -1547,6 +1575,9 @@
     int64_t timestamp_us,
     const RtpTransceiverStatsInfo& stats,
     RTCStatsReport* report) const {
+  RTC_DCHECK(network_thread_->IsCurrent());
+  rtc::Thread::ScopedDisallowBlockingCalls no_blocking_calls;
+
   if (!stats.mid || !stats.transport_name) {
     return;
   }
@@ -1625,6 +1656,9 @@
     int64_t timestamp_us,
     const RtpTransceiverStatsInfo& stats,
     RTCStatsReport* report) const {
+  RTC_DCHECK(network_thread_->IsCurrent());
+  rtc::Thread::ScopedDisallowBlockingCalls no_blocking_calls;
+
   if (!stats.mid || !stats.transport_name) {
     return;
   }
@@ -1705,6 +1739,8 @@
     const std::map<std::string, CertificateStatsPair>& transport_cert_stats,
     RTCStatsReport* report) const {
   RTC_DCHECK(network_thread_->IsCurrent());
+  rtc::Thread::ScopedDisallowBlockingCalls no_blocking_calls;
+
   for (const auto& entry : transport_stats_by_name) {
     const std::string& transport_name = entry.first;
     const cricket::TransportStats& transport_stats = entry.second;
@@ -1796,6 +1832,8 @@
     const std::map<std::string, cricket::TransportStats>&
         transport_stats_by_name) const {
   RTC_DCHECK(network_thread_->IsCurrent());
+  rtc::Thread::ScopedDisallowBlockingCalls no_blocking_calls;
+
   std::map<std::string, CertificateStatsPair> transport_cert_stats;
   for (const auto& entry : transport_stats_by_name) {
     const std::string& transport_name = entry.first;
@@ -1820,9 +1858,10 @@
 }
 
 std::vector<RTCStatsCollector::RtpTransceiverStatsInfo>
-RTCStatsCollector::PrepareTransceiverStatsInfos_s() const {
-  std::vector<RtpTransceiverStatsInfo> transceiver_stats_infos;
+RTCStatsCollector::PrepareTransceiverStatsInfos_s_w() const {
+  RTC_DCHECK(signaling_thread_->IsCurrent());
 
+  std::vector<RtpTransceiverStatsInfo> transceiver_stats_infos;
   // These are used to invoke GetStats for all the media channels together in
   // one worker thread hop.
   std::map<cricket::VoiceMediaChannel*,
@@ -1832,39 +1871,43 @@
            std::unique_ptr<cricket::VideoMediaInfo>>
       video_stats;
 
-  for (const auto& transceiver : pc_->GetTransceiversInternal()) {
-    cricket::MediaType media_type = transceiver->media_type();
+  {
+    rtc::Thread::ScopedDisallowBlockingCalls no_blocking_calls;
 
-    // Prepare stats entry. The TrackMediaInfoMap will be filled in after the
-    // stats have been fetched on the worker thread.
-    transceiver_stats_infos.emplace_back();
-    RtpTransceiverStatsInfo& stats = transceiver_stats_infos.back();
-    stats.transceiver = transceiver->internal();
-    stats.media_type = media_type;
+    for (const auto& transceiver : pc_->GetTransceiversInternal()) {
+      cricket::MediaType media_type = transceiver->media_type();
 
-    cricket::ChannelInterface* channel = transceiver->internal()->channel();
-    if (!channel) {
-      // The remaining fields require a BaseChannel.
-      continue;
-    }
+      // Prepare stats entry. The TrackMediaInfoMap will be filled in after the
+      // stats have been fetched on the worker thread.
+      transceiver_stats_infos.emplace_back();
+      RtpTransceiverStatsInfo& stats = transceiver_stats_infos.back();
+      stats.transceiver = transceiver->internal();
+      stats.media_type = media_type;
 
-    stats.mid = channel->content_name();
-    stats.transport_name = channel->transport_name();
+      cricket::ChannelInterface* channel = transceiver->internal()->channel();
+      if (!channel) {
+        // The remaining fields require a BaseChannel.
+        continue;
+      }
 
-    if (media_type == cricket::MEDIA_TYPE_AUDIO) {
-      auto* voice_channel = static_cast<cricket::VoiceChannel*>(channel);
-      RTC_DCHECK(voice_stats.find(voice_channel->media_channel()) ==
-                 voice_stats.end());
-      voice_stats[voice_channel->media_channel()] =
-          std::make_unique<cricket::VoiceMediaInfo>();
-    } else if (media_type == cricket::MEDIA_TYPE_VIDEO) {
-      auto* video_channel = static_cast<cricket::VideoChannel*>(channel);
-      RTC_DCHECK(video_stats.find(video_channel->media_channel()) ==
-                 video_stats.end());
-      video_stats[video_channel->media_channel()] =
-          std::make_unique<cricket::VideoMediaInfo>();
-    } else {
-      RTC_NOTREACHED();
+      stats.mid = channel->content_name();
+      stats.transport_name = channel->transport_name();
+
+      if (media_type == cricket::MEDIA_TYPE_AUDIO) {
+        auto* voice_channel = static_cast<cricket::VoiceChannel*>(channel);
+        RTC_DCHECK(voice_stats.find(voice_channel->media_channel()) ==
+                   voice_stats.end());
+        voice_stats[voice_channel->media_channel()] =
+            std::make_unique<cricket::VoiceMediaInfo>();
+      } else if (media_type == cricket::MEDIA_TYPE_VIDEO) {
+        auto* video_channel = static_cast<cricket::VideoChannel*>(channel);
+        RTC_DCHECK(video_stats.find(video_channel->media_channel()) ==
+                   video_stats.end());
+        video_stats[video_channel->media_channel()] =
+            std::make_unique<cricket::VideoMediaInfo>();
+      } else {
+        RTC_NOTREACHED();
+      }
     }
   }
 
@@ -1924,6 +1967,9 @@
 }
 
 std::set<std::string> RTCStatsCollector::PrepareTransportNames_s() const {
+  RTC_DCHECK(signaling_thread_->IsCurrent());
+  rtc::Thread::ScopedDisallowBlockingCalls no_blocking_calls;
+
   std::set<std::string> transport_names;
   for (const auto& transceiver : pc_->GetTransceiversInternal()) {
     if (transceiver->internal()->channel()) {