diff --git a/p2p/BUILD.gn b/p2p/BUILD.gn
index 98680f62d2..d9ff347397 100644
--- a/p2p/BUILD.gn
+++ b/p2p/BUILD.gn
@@ -99,6 +99,7 @@ rtc_library("rtc_p2p") {
     "../rtc_base:checks",
     "../rtc_base:rtc_numerics",
     "../rtc_base/experiments:field_trial_parser",
+    "../rtc_base/synchronization:sequence_checker",
 
     # Needed by pseudo_tcp, which should move to a separate target.
     "../rtc_base:safe_minmax",
diff --git a/p2p/base/dtls_transport.cc b/p2p/base/dtls_transport.cc
index 1b7a66000d..52fe5c65a2 100644
--- a/p2p/base/dtls_transport.cc
+++ b/p2p/base/dtls_transport.cc
@@ -73,6 +73,8 @@ rtc::StreamResult StreamInterfaceChannel::Read(void* buffer,
                                                size_t buffer_len,
                                                size_t* read,
                                                int* error) {
+  RTC_DCHECK_RUN_ON(&sequence_checker_);
+
   if (state_ == rtc::SS_CLOSED)
     return rtc::SR_EOS;
   if (state_ == rtc::SS_OPENING)
@@ -89,6 +91,7 @@ rtc::StreamResult StreamInterfaceChannel::Write(const void* data,
                                                 size_t data_len,
                                                 size_t* written,
                                                 int* error) {
+  RTC_DCHECK_RUN_ON(&sequence_checker_);
   // Always succeeds, since this is an unreliable transport anyway.
   // TODO(zhihuang): Should this block if ice_transport_'s temporarily
   // unwritable?
@@ -102,6 +105,7 @@ rtc::StreamResult StreamInterfaceChannel::Write(const void* data,
 }
 
 bool StreamInterfaceChannel::OnPacketReceived(const char* data, size_t size) {
+  RTC_DCHECK_RUN_ON(&sequence_checker_);
   if (packets_.size() > 0) {
     RTC_LOG(LS_WARNING) << "Packet already in queue.";
   }
@@ -118,10 +122,12 @@ bool StreamInterfaceChannel::OnPacketReceived(const char* data, size_t size) {
 }
 
 rtc::StreamState StreamInterfaceChannel::GetState() const {
+  RTC_DCHECK_RUN_ON(&sequence_checker_);
   return state_;
 }
 
 void StreamInterfaceChannel::Close() {
+  RTC_DCHECK_RUN_ON(&sequence_checker_);
   packets_.Clear();
   state_ = rtc::SS_CLOSED;
 }
diff --git a/p2p/base/dtls_transport.h b/p2p/base/dtls_transport.h
index 89156a15d1..430c912330 100644
--- a/p2p/base/dtls_transport.h
+++ b/p2p/base/dtls_transport.h
@@ -24,6 +24,7 @@
 #include "rtc_base/ssl_stream_adapter.h"
 #include "rtc_base/stream.h"
 #include "rtc_base/strings/string_builder.h"
+#include "rtc_base/synchronization/sequence_checker.h"
 #include "rtc_base/thread_checker.h"
 
 namespace rtc {
@@ -54,9 +55,10 @@ class StreamInterfaceChannel : public rtc::StreamInterface {
                           int* error) override;
 
  private:
-  IceTransportInternal* ice_transport_;  // owned by DtlsTransport
-  rtc::StreamState state_;
-  rtc::BufferQueue packets_;
+  webrtc::SequenceChecker sequence_checker_;
+  IceTransportInternal* const ice_transport_;  // owned by DtlsTransport
+  rtc::StreamState state_ RTC_GUARDED_BY(sequence_checker_);
+  rtc::BufferQueue packets_ RTC_GUARDED_BY(sequence_checker_);
 
   RTC_DISALLOW_COPY_AND_ASSIGN(StreamInterfaceChannel);
 };
diff --git a/rtc_base/BUILD.gn b/rtc_base/BUILD.gn
index e15206c75a..a09c06ed75 100644
--- a/rtc_base/BUILD.gn
+++ b/rtc_base/BUILD.gn
@@ -151,6 +151,7 @@ rtc_library("rtc_base_approved") {
     ":stringutils",
     ":thread_checker",
     ":timeutils",
+    "synchronization:sequence_checker",
   ]
 }
 
diff --git a/rtc_base/buffer_queue.cc b/rtc_base/buffer_queue.cc
index adad9dda17..7879e933c7 100644
--- a/rtc_base/buffer_queue.cc
+++ b/rtc_base/buffer_queue.cc
@@ -21,23 +21,20 @@ BufferQueue::BufferQueue(size_t capacity, size_t default_size)
     : capacity_(capacity), default_size_(default_size) {}
 
 BufferQueue::~BufferQueue() {
-  webrtc::MutexLock lock(&mutex_);
-
-  for (Buffer* buffer : queue_) {
+  RTC_DCHECK_RUN_ON(&sequence_checker_);
+  for (Buffer* buffer : queue_)
     delete buffer;
-  }
-  for (Buffer* buffer : free_list_) {
+  for (Buffer* buffer : free_list_)
     delete buffer;
-  }
 }
 
 size_t BufferQueue::size() const {
-  webrtc::MutexLock lock(&mutex_);
+  RTC_DCHECK_RUN_ON(&sequence_checker_);
   return queue_.size();
 }
 
 void BufferQueue::Clear() {
-  webrtc::MutexLock lock(&mutex_);
+  RTC_DCHECK_RUN_ON(&sequence_checker_);
   while (!queue_.empty()) {
     free_list_.push_back(queue_.front());
     queue_.pop_front();
@@ -45,36 +42,30 @@ void BufferQueue::Clear() {
 }
 
 bool BufferQueue::ReadFront(void* buffer, size_t bytes, size_t* bytes_read) {
-  webrtc::MutexLock lock(&mutex_);
-  if (queue_.empty()) {
+  RTC_DCHECK_RUN_ON(&sequence_checker_);
+  if (queue_.empty())
     return false;
-  }
 
-  bool was_writable = queue_.size() < capacity_;
   Buffer* packet = queue_.front();
   queue_.pop_front();
 
   bytes = std::min(bytes, packet->size());
   memcpy(buffer, packet->data(), bytes);
-  if (bytes_read) {
+
+  if (bytes_read)
     *bytes_read = bytes;
-  }
+
   free_list_.push_back(packet);
-  if (!was_writable) {
-    NotifyWritableForTest();
-  }
   return true;
 }
 
 bool BufferQueue::WriteBack(const void* buffer,
                             size_t bytes,
                             size_t* bytes_written) {
-  webrtc::MutexLock lock(&mutex_);
-  if (queue_.size() == capacity_) {
+  RTC_DCHECK_RUN_ON(&sequence_checker_);
+  if (queue_.size() == capacity_)
     return false;
-  }
 
-  bool was_readable = !queue_.empty();
   Buffer* packet;
   if (!free_list_.empty()) {
     packet = free_list_.back();
@@ -84,13 +75,10 @@ bool BufferQueue::WriteBack(const void* buffer,
   }
 
   packet->SetData(static_cast<const uint8_t*>(buffer), bytes);
-  if (bytes_written) {
+  if (bytes_written)
     *bytes_written = bytes;
-  }
+
   queue_.push_back(packet);
-  if (!was_readable) {
-    NotifyReadableForTest();
-  }
   return true;
 }
 
diff --git a/rtc_base/buffer_queue.h b/rtc_base/buffer_queue.h
index 29d1a5b136..24a9b04dc2 100644
--- a/rtc_base/buffer_queue.h
+++ b/rtc_base/buffer_queue.h
@@ -18,16 +18,16 @@
 
 #include "rtc_base/buffer.h"
 #include "rtc_base/constructor_magic.h"
-#include "rtc_base/synchronization/mutex.h"
+#include "rtc_base/synchronization/sequence_checker.h"
 #include "rtc_base/thread_annotations.h"
 
 namespace rtc {
 
-class BufferQueue {
+class BufferQueue final {
  public:
   // Creates a buffer queue with a given capacity and default buffer size.
   BufferQueue(size_t capacity, size_t default_size);
-  virtual ~BufferQueue();
+  ~BufferQueue();
 
   // Return number of queued buffers.
   size_t size() const;
@@ -44,17 +44,22 @@ class BufferQueue {
   // Returns true unless no data could be written.
   bool WriteBack(const void* data, size_t bytes, size_t* bytes_written);
 
- protected:
-  // These methods are called when the state of the queue changes.
-  virtual void NotifyReadableForTest() {}
-  virtual void NotifyWritableForTest() {}
+  bool is_writable() const {
+    RTC_DCHECK_RUN_ON(&sequence_checker_);
+    return queue_.size() < capacity_;
+  }
+
+  bool is_readable() const {
+    RTC_DCHECK_RUN_ON(&sequence_checker_);
+    return !queue_.empty();
+  }
 
  private:
-  size_t capacity_;
-  size_t default_size_;
-  mutable webrtc::Mutex mutex_;
-  std::deque<Buffer*> queue_ RTC_GUARDED_BY(mutex_);
-  std::vector<Buffer*> free_list_ RTC_GUARDED_BY(mutex_);
+  webrtc::SequenceChecker sequence_checker_;
+  const size_t capacity_;
+  const size_t default_size_;
+  std::deque<Buffer*> queue_ RTC_GUARDED_BY(sequence_checker_);
+  std::vector<Buffer*> free_list_ RTC_GUARDED_BY(sequence_checker_);
 
   RTC_DISALLOW_COPY_AND_ASSIGN(BufferQueue);
 };
diff --git a/rtc_base/ssl_stream_adapter_unittest.cc b/rtc_base/ssl_stream_adapter_unittest.cc
index c1017b773d..bfbaf0f301 100644
--- a/rtc_base/ssl_stream_adapter_unittest.cc
+++ b/rtc_base/ssl_stream_adapter_unittest.cc
@@ -231,10 +231,10 @@ class SSLDummyStreamTLS : public SSLDummyStreamBase {
       : SSLDummyStreamBase(test, side, in, out) {}
 };
 
-class BufferQueueStream : public rtc::BufferQueue, public rtc::StreamInterface {
+class BufferQueueStream : public rtc::StreamInterface {
  public:
   BufferQueueStream(size_t capacity, size_t default_size)
-      : rtc::BufferQueue(capacity, default_size) {}
+      : buffer_(capacity, default_size) {}
 
   // Implementation of abstract StreamInterface methods.
 
@@ -246,9 +246,13 @@ class BufferQueueStream : public rtc::BufferQueue, public rtc::StreamInterface {
                          size_t buffer_len,
                          size_t* read,
                          int* error) override {
-    if (!ReadFront(buffer, buffer_len, read)) {
+    const bool was_writable = buffer_.is_writable();
+    if (!buffer_.ReadFront(buffer, buffer_len, read))
       return rtc::SR_BLOCK;
-    }
+
+    if (!was_writable)
+      NotifyWritableForTest();
+
     return rtc::SR_SUCCESS;
   }
 
@@ -257,9 +261,13 @@ class BufferQueueStream : public rtc::BufferQueue, public rtc::StreamInterface {
                           size_t data_len,
                           size_t* written,
                           int* error) override {
-    if (!WriteBack(data, data_len, written)) {
+    const bool was_readable = buffer_.is_readable();
+    if (!buffer_.WriteBack(data, data_len, written))
       return rtc::SR_BLOCK;
-    }
+
+    if (!was_readable)
+      NotifyReadableForTest();
+
     return rtc::SR_SUCCESS;
   }
 
@@ -267,9 +275,12 @@ class BufferQueueStream : public rtc::BufferQueue, public rtc::StreamInterface {
   void Close() override {}
 
  protected:
-  void NotifyReadableForTest() override { PostEvent(rtc::SE_READ, 0); }
+  void NotifyReadableForTest() { PostEvent(rtc::SE_READ, 0); }
 
-  void NotifyWritableForTest() override { PostEvent(rtc::SE_WRITE, 0); }
+  void NotifyWritableForTest() { PostEvent(rtc::SE_WRITE, 0); }
+
+ private:
+  rtc::BufferQueue buffer_;
 };
 
 class SSLDummyStreamDTLS : public SSLDummyStreamBase {