diff --git a/api/rtp_headers.h b/api/rtp_headers.h
index 04c3853..13bc4f9 100644
--- a/api/rtp_headers.h
+++ b/api/rtp_headers.h
@@ -13,7 +13,7 @@
 
 #include <stddef.h>
 #include <stdint.h>
-#include <string.h>
+#include <string>
 
 #include "absl/types/optional.h"
 #include "api/array_view.h"
@@ -26,62 +26,6 @@
 
 namespace webrtc {
 
-// Class to represent the value of RTP header extensions that are
-// variable-length strings (e.g., RtpStreamId and RtpMid).
-// Unlike std::string, it can be copied with memcpy and cleared with memset.
-//
-// Empty value represents unset header extension (use empty() to query).
-class StringRtpHeaderExtension {
- public:
-  // String RTP header extensions are limited to 16 bytes because it is the
-  // maximum length that can be encoded with one-byte header extensions.
-  static constexpr size_t kMaxSize = 16;
-
-  static bool IsLegalMidName(rtc::ArrayView<const char> name);
-  static bool IsLegalRsidName(rtc::ArrayView<const char> name);
-
-  // TODO(bugs.webrtc.org/9537): Deprecate and remove when third parties have
-  // migrated to "IsLegalRsidName".
-  static bool IsLegalName(rtc::ArrayView<const char> name) {
-    return IsLegalRsidName(name);
-  }
-
-  StringRtpHeaderExtension() { value_[0] = 0; }
-  explicit StringRtpHeaderExtension(rtc::ArrayView<const char> value) {
-    Set(value.data(), value.size());
-  }
-  StringRtpHeaderExtension(const StringRtpHeaderExtension&) = default;
-  StringRtpHeaderExtension& operator=(const StringRtpHeaderExtension&) =
-      default;
-
-  bool empty() const { return value_[0] == 0; }
-  const char* data() const { return value_; }
-  size_t size() const { return strnlen(value_, kMaxSize); }
-
-  void Set(rtc::ArrayView<const uint8_t> value) {
-    Set(reinterpret_cast<const char*>(value.data()), value.size());
-  }
-  void Set(const char* data, size_t size);
-
-  friend bool operator==(const StringRtpHeaderExtension& lhs,
-                         const StringRtpHeaderExtension& rhs) {
-    return strncmp(lhs.value_, rhs.value_, kMaxSize) == 0;
-  }
-  friend bool operator!=(const StringRtpHeaderExtension& lhs,
-                         const StringRtpHeaderExtension& rhs) {
-    return !(lhs == rhs);
-  }
-
- private:
-  char value_[kMaxSize];
-};
-
-// StreamId represents RtpStreamId which is a string.
-typedef StringRtpHeaderExtension StreamId;
-
-// Mid represents RtpMid which is a string.
-typedef StringRtpHeaderExtension Mid;
-
 struct FeedbackRequest {
   // Determines whether the recv delta as specified in
   // https://tools.ietf.org/html/draft-holmer-rmcat-transport-wide-cc-extensions-01
@@ -134,12 +78,12 @@
   // For identification of a stream when ssrc is not signaled. See
   // https://tools.ietf.org/html/draft-ietf-avtext-rid-09
   // TODO(danilchap): Update url from draft to release version.
-  StreamId stream_id;
-  StreamId repaired_stream_id;
+  std::string stream_id;
+  std::string repaired_stream_id;
 
   // For identifying the media section used to interpret this RTP packet. See
   // https://tools.ietf.org/html/draft-ietf-mmusic-sdp-bundle-negotiation-38
-  Mid mid;
+  std::string mid;
 
   absl::optional<ColorSpace> color_space;
 };
diff --git a/call/rtcp_demuxer_unittest.cc b/call/rtcp_demuxer_unittest.cc
index bed2819..5060c7b 100644
--- a/call/rtcp_demuxer_unittest.cc
+++ b/call/rtcp_demuxer_unittest.cc
@@ -16,6 +16,7 @@
 #include "api/rtp_headers.h"
 #include "call/rtcp_packet_sink_interface.h"
 #include "modules/rtp_rtcp/source/rtcp_packet/bye.h"
+#include "modules/rtp_rtcp/source/rtp_header_extensions.h"
 #include "rtc_base/arraysize.h"
 #include "rtc_base/buffer.h"
 #include "rtc_base/checks.h"
@@ -494,7 +495,7 @@
 
 TEST_F(RtcpDemuxerTest, RsidMustNotExceedMaximumLength) {
   MockRtcpPacketSink sink;
-  std::string rsid(StreamId::kMaxSize + 1, 'a');
+  std::string rsid(BaseRtpStringExtension::kMaxValueSizeBytes + 1, 'a');
   EXPECT_DEATH(AddRsidSink(rsid, &sink), "");
 }
 
diff --git a/call/rtp_demuxer_unittest.cc b/call/rtp_demuxer_unittest.cc
index 3b8200e..fbca494 100644
--- a/call/rtp_demuxer_unittest.cc
+++ b/call/rtp_demuxer_unittest.cc
@@ -1497,13 +1497,13 @@
 
 TEST_F(RtpDemuxerTest, RsidMustNotExceedMaximumLength) {
   MockRtpPacketSink sink;
-  std::string rsid(StreamId::kMaxSize + 1, 'a');
+  std::string rsid(BaseRtpStringExtension::kMaxValueSizeBytes + 1, 'a');
   EXPECT_DEATH(AddSinkOnlyRsid(rsid, &sink), "");
 }
 
 TEST_F(RtpDemuxerTest, MidMustNotExceedMaximumLength) {
   MockRtpPacketSink sink;
-  std::string mid(Mid::kMaxSize + 1, 'a');
+  std::string mid(BaseRtpStringExtension::kMaxValueSizeBytes + 1, 'a');
   EXPECT_DEATH(AddSinkOnlyMid(mid, &sink), "");
 }
 
diff --git a/modules/rtp_rtcp/include/rtp_rtcp_defines.cc b/modules/rtp_rtcp/include/rtp_rtcp_defines.cc
index 20bd1e7..3b8972f 100644
--- a/modules/rtp_rtcp/include/rtp_rtcp_defines.cc
+++ b/modules/rtp_rtcp/include/rtp_rtcp_defines.cc
@@ -24,47 +24,24 @@
 constexpr size_t kMidRsidMaxSize = 16;
 
 // Check if passed character is a "token-char" from RFC 4566.
-static bool IsTokenChar(char ch) {
+bool IsTokenChar(char ch) {
   return ch == 0x21 || (ch >= 0x23 && ch <= 0x27) || ch == 0x2a || ch == 0x2b ||
          ch == 0x2d || ch == 0x2e || (ch >= 0x30 && ch <= 0x39) ||
          (ch >= 0x41 && ch <= 0x5a) || (ch >= 0x5e && ch <= 0x7e);
 }
-
 }  // namespace
 
-StreamDataCounters::StreamDataCounters() : first_packet_time_ms(-1) {}
-
-constexpr size_t StreamId::kMaxSize;
-
 bool IsLegalMidName(absl::string_view name) {
   return (name.size() <= kMidRsidMaxSize && name.size() > 0 &&
           std::all_of(name.data(), name.data() + name.size(), IsTokenChar));
 }
 
-bool StreamId::IsLegalMidName(rtc::ArrayView<const char> name) {
-  return ::webrtc::IsLegalMidName(absl::string_view(name.data(), name.size()));
-}
-
 bool IsLegalRsidName(absl::string_view name) {
   return (name.size() <= kMidRsidMaxSize && name.size() > 0 &&
           std::all_of(name.data(), name.data() + name.size(), isalnum));
 }
 
-bool StreamId::IsLegalRsidName(rtc::ArrayView<const char> name) {
-  return ::webrtc::IsLegalRsidName(absl::string_view(name.data(), name.size()));
-}
-
-void StreamId::Set(const char* data, size_t size) {
-  // If |data| contains \0, the stream id size might become less than |size|.
-  RTC_CHECK_LE(size, kMaxSize);
-  memcpy(value_, data, size);
-  if (size < kMaxSize)
-    value_[size] = 0;
-}
-
-// StreamId is used as member of RTPHeader that is sometimes copied with memcpy
-// and thus assume trivial destructibility.
-static_assert(std::is_trivially_destructible<StreamId>::value, "");
+StreamDataCounters::StreamDataCounters() : first_packet_time_ms(-1) {}
 
 PacketFeedback::PacketFeedback(int64_t arrival_time_ms,
                                uint16_t sequence_number)
diff --git a/modules/rtp_rtcp/source/rtp_header_extensions.cc b/modules/rtp_rtcp/source/rtp_header_extensions.cc
index 1d76ff3..9045003 100644
--- a/modules/rtp_rtcp/source/rtp_header_extensions.cc
+++ b/modules/rtp_rtcp/source/rtp_header_extensions.cc
@@ -727,24 +727,6 @@
 }
 
 bool BaseRtpStringExtension::Parse(rtc::ArrayView<const uint8_t> data,
-                                   StringRtpHeaderExtension* str) {
-  if (data.empty() || data[0] == 0)  // Valid string extension can't be empty.
-    return false;
-  str->Set(data);
-  RTC_DCHECK(!str->empty());
-  return true;
-}
-
-bool BaseRtpStringExtension::Write(rtc::ArrayView<uint8_t> data,
-                                   const StringRtpHeaderExtension& str) {
-  RTC_DCHECK_EQ(data.size(), str.size());
-  RTC_DCHECK_GE(str.size(), 1);
-  RTC_DCHECK_LE(str.size(), StringRtpHeaderExtension::kMaxSize);
-  memcpy(data.data(), str.data(), str.size());
-  return true;
-}
-
-bool BaseRtpStringExtension::Parse(rtc::ArrayView<const uint8_t> data,
                                    std::string* str) {
   if (data.empty() || data[0] == 0)  // Valid string extension can't be empty.
     return false;
@@ -758,7 +740,7 @@
 
 bool BaseRtpStringExtension::Write(rtc::ArrayView<uint8_t> data,
                                    const std::string& str) {
-  if (str.size() > StringRtpHeaderExtension::kMaxSize) {
+  if (str.size() > kMaxValueSizeBytes) {
     return false;
   }
   RTC_DCHECK_EQ(data.size(), str.size());
diff --git a/modules/rtp_rtcp/source/rtp_header_extensions.h b/modules/rtp_rtcp/source/rtp_header_extensions.h
index 8aacb9a..c77492e 100644
--- a/modules/rtp_rtcp/source/rtp_header_extensions.h
+++ b/modules/rtp_rtcp/source/rtp_header_extensions.h
@@ -259,14 +259,6 @@
   // maximum length that can be encoded with one-byte header extensions.
   static constexpr uint8_t kMaxValueSizeBytes = 16;
 
-  static bool Parse(rtc::ArrayView<const uint8_t> data,
-                    StringRtpHeaderExtension* str);
-  static size_t ValueSize(const StringRtpHeaderExtension& str) {
-    return str.size();
-  }
-  static bool Write(rtc::ArrayView<uint8_t> data,
-                    const StringRtpHeaderExtension& str);
-
   static bool Parse(rtc::ArrayView<const uint8_t> data, std::string* str);
   static size_t ValueSize(const std::string& str) { return str.size(); }
   static bool Write(rtc::ArrayView<uint8_t> data, const std::string& str);
diff --git a/modules/rtp_rtcp/source/rtp_utility.cc b/modules/rtp_rtcp/source/rtp_utility.cc
index a1a3e35..b04ac4b 100644
--- a/modules/rtp_rtcp/source/rtp_utility.cc
+++ b/modules/rtp_rtcp/source/rtp_utility.cc
@@ -12,6 +12,7 @@
 
 #include <assert.h>
 #include <stddef.h>
+#include <string>
 
 #include "api/array_view.h"
 #include "api/video/video_content_type.h"
@@ -494,16 +495,30 @@
           break;
         }
         case kRtpExtensionRtpStreamId: {
-          header->extension.stream_id.Set(rtc::MakeArrayView(ptr, len + 1));
+          std::string name(reinterpret_cast<const char*>(ptr), len + 1);
+          if (IsLegalRsidName(name)) {
+            header->extension.stream_id = name;
+          } else {
+            RTC_LOG(LS_WARNING) << "Incorrect RtpStreamId";
+          }
           break;
         }
         case kRtpExtensionRepairedRtpStreamId: {
-          header->extension.repaired_stream_id.Set(
-              rtc::MakeArrayView(ptr, len + 1));
+          std::string name(reinterpret_cast<const char*>(ptr), len + 1);
+          if (IsLegalRsidName(name)) {
+            header->extension.repaired_stream_id = name;
+          } else {
+            RTC_LOG(LS_WARNING) << "Incorrect RepairedRtpStreamId";
+          }
           break;
         }
         case kRtpExtensionMid: {
-          header->extension.mid.Set(rtc::MakeArrayView(ptr, len + 1));
+          std::string name(reinterpret_cast<const char*>(ptr), len + 1);
+          if (IsLegalMidName(name)) {
+            header->extension.mid = name;
+          } else {
+            RTC_LOG(LS_WARNING) << "Incorrect Mid";
+          }
           break;
         }
         case kRtpExtensionGenericFrameDescriptor00:
diff --git a/modules/rtp_rtcp/source/rtp_utility_unittest.cc b/modules/rtp_rtcp/source/rtp_utility_unittest.cc
index e1bcfb7..f5ade3d 100644
--- a/modules/rtp_rtcp/source/rtp_utility_unittest.cc
+++ b/modules/rtp_rtcp/source/rtp_utility_unittest.cc
@@ -204,8 +204,8 @@
             header.extension.playout_delay.min_ms);
   EXPECT_EQ(0x876 * PlayoutDelayLimits::kGranularityMs,
             header.extension.playout_delay.max_ms);
-  EXPECT_EQ(header.extension.stream_id, StreamId("rtx"));
-  EXPECT_EQ(header.extension.repaired_stream_id, StreamId("stream"));
+  EXPECT_EQ(header.extension.stream_id, "rtx");
+  EXPECT_EQ(header.extension.repaired_stream_id, "stream");
 }
 
 TEST(RtpHeaderParser, ParseMalformedRsidExtensions) {
@@ -230,7 +230,7 @@
 
   EXPECT_TRUE(parser.Parse(&header, &extensions));
   EXPECT_TRUE(header.extension.stream_id.empty());
-  EXPECT_EQ(header.extension.repaired_stream_id, StreamId("str"));
+  EXPECT_TRUE(header.extension.repaired_stream_id.empty());
 }
 
 TEST(RtpHeaderParser, ParseWithCsrcsExtensionAndPadding) {