diff --git a/rtc_base/BUILD.gn b/rtc_base/BUILD.gn
index 3f02fb7..20ba824 100644
--- a/rtc_base/BUILD.gn
+++ b/rtc_base/BUILD.gn
@@ -960,6 +960,8 @@
     "firewallsocketserver.h",
     "gunit.cc",
     "gunit.h",
+    "memory_stream.cc",
+    "memory_stream.h",
     "memory_usage.cc",
     "memory_usage.h",
     "natserver.cc",
diff --git a/rtc_base/memory_stream.cc b/rtc_base/memory_stream.cc
new file mode 100644
index 0000000..541de07
--- /dev/null
+++ b/rtc_base/memory_stream.cc
@@ -0,0 +1,143 @@
+/*
+ *  Copyright 2018 The WebRTC Project Authors. All rights reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include <algorithm>
+
+#include "rtc_base/memory_stream.h"
+
+namespace rtc {
+
+StreamState MemoryStream::GetState() const {
+  return SS_OPEN;
+}
+
+StreamResult MemoryStream::Read(void* buffer,
+                                size_t bytes,
+                                size_t* bytes_read,
+                                int* error) {
+  if (seek_position_ >= data_length_) {
+    return SR_EOS;
+  }
+  size_t available = data_length_ - seek_position_;
+  if (bytes > available) {
+    // Read partial buffer
+    bytes = available;
+  }
+  memcpy(buffer, &buffer_[seek_position_], bytes);
+  seek_position_ += bytes;
+  if (bytes_read) {
+    *bytes_read = bytes;
+  }
+  return SR_SUCCESS;
+}
+
+StreamResult MemoryStream::Write(const void* buffer,
+                                 size_t bytes,
+                                 size_t* bytes_written,
+                                 int* error) {
+  size_t available = buffer_length_ - seek_position_;
+  if (0 == available) {
+    // Increase buffer size to the larger of:
+    // a) new position rounded up to next 256 bytes
+    // b) double the previous length
+    size_t new_buffer_length =
+        std::max(((seek_position_ + bytes) | 0xFF) + 1, buffer_length_ * 2);
+    StreamResult result = DoReserve(new_buffer_length, error);
+    if (SR_SUCCESS != result) {
+      return result;
+    }
+    RTC_DCHECK(buffer_length_ >= new_buffer_length);
+    available = buffer_length_ - seek_position_;
+  }
+
+  if (bytes > available) {
+    bytes = available;
+  }
+  memcpy(&buffer_[seek_position_], buffer, bytes);
+  seek_position_ += bytes;
+  if (data_length_ < seek_position_) {
+    data_length_ = seek_position_;
+  }
+  if (bytes_written) {
+    *bytes_written = bytes;
+  }
+  return SR_SUCCESS;
+}
+
+void MemoryStream::Close() {
+  // nothing to do
+}
+
+bool MemoryStream::SetPosition(size_t position) {
+  if (position > data_length_)
+    return false;
+  seek_position_ = position;
+  return true;
+}
+
+bool MemoryStream::GetPosition(size_t* position) const {
+  if (position)
+    *position = seek_position_;
+  return true;
+}
+
+bool MemoryStream::GetSize(size_t* size) const {
+  if (size)
+    *size = data_length_;
+  return true;
+}
+
+bool MemoryStream::ReserveSize(size_t size) {
+  return (SR_SUCCESS == DoReserve(size, nullptr));
+}
+
+///////////////////////////////////////////////////////////////////////////////
+
+MemoryStream::MemoryStream() {}
+
+MemoryStream::MemoryStream(const char* data) {
+  SetData(data, strlen(data));
+}
+
+MemoryStream::MemoryStream(const void* data, size_t length) {
+  SetData(data, length);
+}
+
+MemoryStream::~MemoryStream() {
+  delete[] buffer_;
+}
+
+void MemoryStream::SetData(const void* data, size_t length) {
+  data_length_ = buffer_length_ = length;
+  delete[] buffer_;
+  buffer_ = new char[buffer_length_];
+  memcpy(buffer_, data, data_length_);
+  seek_position_ = 0;
+}
+
+StreamResult MemoryStream::DoReserve(size_t size, int* error) {
+  if (buffer_length_ >= size)
+    return SR_SUCCESS;
+
+  if (char* new_buffer = new char[size]) {
+    memcpy(new_buffer, buffer_, data_length_);
+    delete[] buffer_;
+    buffer_ = new_buffer;
+    buffer_length_ = size;
+    return SR_SUCCESS;
+  }
+
+  if (error) {
+    *error = ENOMEM;
+  }
+  return SR_ERROR;
+}
+
+}  // namespace rtc
diff --git a/rtc_base/memory_stream.h b/rtc_base/memory_stream.h
new file mode 100644
index 0000000..936f71b
--- /dev/null
+++ b/rtc_base/memory_stream.h
@@ -0,0 +1,59 @@
+/*
+ *  Copyright 2018 The WebRTC Project Authors. All rights reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#ifndef RTC_BASE_MEMORY_STREAM_H_
+#define RTC_BASE_MEMORY_STREAM_H_
+
+#include "rtc_base/stream.h"
+
+namespace rtc {
+
+// MemoryStream dynamically resizes to accomodate written data.
+
+class MemoryStream final : public StreamInterface {
+ public:
+  MemoryStream();
+  explicit MemoryStream(const char* data);  // Calls SetData(data, strlen(data))
+  MemoryStream(const void* data, size_t length);  // Calls SetData(data, length)
+  ~MemoryStream() override;
+
+  StreamState GetState() const override;
+  StreamResult Read(void* buffer,
+                    size_t bytes,
+                    size_t* bytes_read,
+                    int* error) override;
+  StreamResult Write(const void* buffer,
+                     size_t bytes,
+                     size_t* bytes_written,
+                     int* error) override;
+  void Close() override;
+  bool SetPosition(size_t position) override;
+  bool GetPosition(size_t* position) const override;
+  bool GetSize(size_t* size) const override;
+  bool ReserveSize(size_t size) override;
+
+  char* GetBuffer() { return buffer_; }
+  const char* GetBuffer() const { return buffer_; }
+
+  void SetData(const void* data, size_t length);
+
+ private:
+  StreamResult DoReserve(size_t size, int* error);
+
+  // Invariant: 0 <= seek_position <= data_length_ <= buffer_length_
+  char* buffer_ = nullptr;
+  size_t buffer_length_ = 0;
+  size_t data_length_ = 0;
+  size_t seek_position_ = 0;
+};
+
+}  // namespace rtc
+
+#endif  // RTC_BASE_MEMORY_STREAM_H_
diff --git a/rtc_base/sslstreamadapter_unittest.cc b/rtc_base/sslstreamadapter_unittest.cc
index ff4c7a0..6fbb1d7 100644
--- a/rtc_base/sslstreamadapter_unittest.cc
+++ b/rtc_base/sslstreamadapter_unittest.cc
@@ -17,6 +17,7 @@
 #include "rtc_base/checks.h"
 #include "rtc_base/gunit.h"
 #include "rtc_base/helpers.h"
+#include "rtc_base/memory_stream.h"
 #include "rtc_base/messagedigest.h"
 #include "rtc_base/ssladapter.h"
 #include "rtc_base/sslidentity.h"
diff --git a/rtc_base/stream.cc b/rtc_base/stream.cc
index c149639..783625c 100644
--- a/rtc_base/stream.cc
+++ b/rtc_base/stream.cc
@@ -348,143 +348,6 @@
 }
 
 ///////////////////////////////////////////////////////////////////////////////
-// MemoryStream
-///////////////////////////////////////////////////////////////////////////////
-
-MemoryStreamBase::MemoryStreamBase()
-    : buffer_(nullptr), buffer_length_(0), data_length_(0), seek_position_(0) {}
-
-StreamState MemoryStreamBase::GetState() const {
-  return SS_OPEN;
-}
-
-StreamResult MemoryStreamBase::Read(void* buffer,
-                                    size_t bytes,
-                                    size_t* bytes_read,
-                                    int* error) {
-  if (seek_position_ >= data_length_) {
-    return SR_EOS;
-  }
-  size_t available = data_length_ - seek_position_;
-  if (bytes > available) {
-    // Read partial buffer
-    bytes = available;
-  }
-  memcpy(buffer, &buffer_[seek_position_], bytes);
-  seek_position_ += bytes;
-  if (bytes_read) {
-    *bytes_read = bytes;
-  }
-  return SR_SUCCESS;
-}
-
-StreamResult MemoryStreamBase::Write(const void* buffer,
-                                     size_t bytes,
-                                     size_t* bytes_written,
-                                     int* error) {
-  size_t available = buffer_length_ - seek_position_;
-  if (0 == available) {
-    // Increase buffer size to the larger of:
-    // a) new position rounded up to next 256 bytes
-    // b) double the previous length
-    size_t new_buffer_length =
-        std::max(((seek_position_ + bytes) | 0xFF) + 1, buffer_length_ * 2);
-    StreamResult result = DoReserve(new_buffer_length, error);
-    if (SR_SUCCESS != result) {
-      return result;
-    }
-    RTC_DCHECK(buffer_length_ >= new_buffer_length);
-    available = buffer_length_ - seek_position_;
-  }
-
-  if (bytes > available) {
-    bytes = available;
-  }
-  memcpy(&buffer_[seek_position_], buffer, bytes);
-  seek_position_ += bytes;
-  if (data_length_ < seek_position_) {
-    data_length_ = seek_position_;
-  }
-  if (bytes_written) {
-    *bytes_written = bytes;
-  }
-  return SR_SUCCESS;
-}
-
-void MemoryStreamBase::Close() {
-  // nothing to do
-}
-
-bool MemoryStreamBase::SetPosition(size_t position) {
-  if (position > data_length_)
-    return false;
-  seek_position_ = position;
-  return true;
-}
-
-bool MemoryStreamBase::GetPosition(size_t* position) const {
-  if (position)
-    *position = seek_position_;
-  return true;
-}
-
-bool MemoryStreamBase::GetSize(size_t* size) const {
-  if (size)
-    *size = data_length_;
-  return true;
-}
-
-bool MemoryStreamBase::ReserveSize(size_t size) {
-  return (SR_SUCCESS == DoReserve(size, nullptr));
-}
-
-StreamResult MemoryStreamBase::DoReserve(size_t size, int* error) {
-  return (buffer_length_ >= size) ? SR_SUCCESS : SR_EOS;
-}
-
-///////////////////////////////////////////////////////////////////////////////
-
-MemoryStream::MemoryStream() {}
-
-MemoryStream::MemoryStream(const char* data) {
-  SetData(data, strlen(data));
-}
-
-MemoryStream::MemoryStream(const void* data, size_t length) {
-  SetData(data, length);
-}
-
-MemoryStream::~MemoryStream() {
-  delete[] buffer_;
-}
-
-void MemoryStream::SetData(const void* data, size_t length) {
-  data_length_ = buffer_length_ = length;
-  delete[] buffer_;
-  buffer_ = new char[buffer_length_];
-  memcpy(buffer_, data, data_length_);
-  seek_position_ = 0;
-}
-
-StreamResult MemoryStream::DoReserve(size_t size, int* error) {
-  if (buffer_length_ >= size)
-    return SR_SUCCESS;
-
-  if (char* new_buffer = new char[size]) {
-    memcpy(new_buffer, buffer_, data_length_);
-    delete[] buffer_;
-    buffer_ = new_buffer;
-    buffer_length_ = size;
-    return SR_SUCCESS;
-  }
-
-  if (error) {
-    *error = ENOMEM;
-  }
-  return SR_ERROR;
-}
-
-///////////////////////////////////////////////////////////////////////////////
 // FifoBuffer
 ///////////////////////////////////////////////////////////////////////////////
 
diff --git a/rtc_base/stream.h b/rtc_base/stream.h
index 2e72ce3..43e7f58 100644
--- a/rtc_base/stream.h
+++ b/rtc_base/stream.h
@@ -261,63 +261,6 @@
   RTC_DISALLOW_COPY_AND_ASSIGN(FileStream);
 };
 
-///////////////////////////////////////////////////////////////////////////////
-// MemoryStream is a simple implementation of a StreamInterface over in-memory
-// data.  Data is read and written at the current seek position.  Reads return
-// end-of-stream when they reach the end of data.  Writes actually extend the
-// end of data mark.
-///////////////////////////////////////////////////////////////////////////////
-
-class MemoryStreamBase : public StreamInterface {
- public:
-  StreamState GetState() const override;
-  StreamResult Read(void* buffer,
-                    size_t bytes,
-                    size_t* bytes_read,
-                    int* error) override;
-  StreamResult Write(const void* buffer,
-                     size_t bytes,
-                     size_t* bytes_written,
-                     int* error) override;
-  void Close() override;
-  bool SetPosition(size_t position) override;
-  bool GetPosition(size_t* position) const override;
-  bool GetSize(size_t* size) const override;
-  bool ReserveSize(size_t size) override;
-
-  char* GetBuffer() { return buffer_; }
-  const char* GetBuffer() const { return buffer_; }
-
- protected:
-  MemoryStreamBase();
-
-  virtual StreamResult DoReserve(size_t size, int* error);
-
-  // Invariant: 0 <= seek_position <= data_length_ <= buffer_length_
-  char* buffer_;
-  size_t buffer_length_;
-  size_t data_length_;
-  size_t seek_position_;
-
- private:
-  RTC_DISALLOW_COPY_AND_ASSIGN(MemoryStreamBase);
-};
-
-// MemoryStream dynamically resizes to accomodate written data.
-
-class MemoryStream : public MemoryStreamBase {
- public:
-  MemoryStream();
-  explicit MemoryStream(const char* data);  // Calls SetData(data, strlen(data))
-  MemoryStream(const void* data, size_t length);  // Calls SetData(data, length)
-  ~MemoryStream() override;
-
-  void SetData(const void* data, size_t length);
-
- protected:
-  StreamResult DoReserve(size_t size, int* error) override;
-};
-
 // FifoBuffer allows for efficient, thread-safe buffering of data between
 // writer and reader. As the data can wrap around the end of the buffer,
 // MemoryStreamBase can't help us here.