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diff --git a/third_party/libwebrtc/pc/jsep_session_description.cc b/third_party/libwebrtc/pc/jsep_session_description.cc
new file mode 100644
index 0000000000..4c57396f08
--- /dev/null
+++ b/third_party/libwebrtc/pc/jsep_session_description.cc
@@ -0,0 +1,370 @@
+/*
+ *  Copyright 2012 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 "api/jsep_session_description.h"
+
+#include <memory>
+#include <utility>
+
+#include "absl/types/optional.h"
+#include "p2p/base/p2p_constants.h"
+#include "p2p/base/port.h"
+#include "p2p/base/transport_description.h"
+#include "p2p/base/transport_info.h"
+#include "pc/media_session.h"  // IWYU pragma: keep
+#include "pc/webrtc_sdp.h"
+#include "rtc_base/checks.h"
+#include "rtc_base/ip_address.h"
+#include "rtc_base/logging.h"
+#include "rtc_base/net_helper.h"
+#include "rtc_base/socket_address.h"
+
+using cricket::SessionDescription;
+
+namespace webrtc {
+namespace {
+
+// RFC 5245
+// It is RECOMMENDED that default candidates be chosen based on the
+// likelihood of those candidates to work with the peer that is being
+// contacted.  It is RECOMMENDED that relayed > reflexive > host.
+constexpr int kPreferenceUnknown = 0;
+constexpr int kPreferenceHost = 1;
+constexpr int kPreferenceReflexive = 2;
+constexpr int kPreferenceRelayed = 3;
+
+constexpr char kDummyAddress[] = "0.0.0.0";
+constexpr int kDummyPort = 9;
+
+int GetCandidatePreferenceFromType(const std::string& type) {
+  int preference = kPreferenceUnknown;
+  if (type == cricket::LOCAL_PORT_TYPE) {
+    preference = kPreferenceHost;
+  } else if (type == cricket::STUN_PORT_TYPE) {
+    preference = kPreferenceReflexive;
+  } else if (type == cricket::RELAY_PORT_TYPE) {
+    preference = kPreferenceRelayed;
+  } else {
+    preference = kPreferenceUnknown;
+  }
+  return preference;
+}
+
+// Update the connection address for the MediaContentDescription based on the
+// candidates.
+void UpdateConnectionAddress(
+    const JsepCandidateCollection& candidate_collection,
+    cricket::MediaContentDescription* media_desc) {
+  int port = kDummyPort;
+  std::string ip = kDummyAddress;
+  std::string hostname;
+  int current_preference = kPreferenceUnknown;
+  int current_family = AF_UNSPEC;
+  for (size_t i = 0; i < candidate_collection.count(); ++i) {
+    const IceCandidateInterface* jsep_candidate = candidate_collection.at(i);
+    if (jsep_candidate->candidate().component() !=
+        cricket::ICE_CANDIDATE_COMPONENT_RTP) {
+      continue;
+    }
+    // Default destination should be UDP only.
+    if (jsep_candidate->candidate().protocol() != cricket::UDP_PROTOCOL_NAME) {
+      continue;
+    }
+    const int preference =
+        GetCandidatePreferenceFromType(jsep_candidate->candidate().type());
+    const int family = jsep_candidate->candidate().address().ipaddr().family();
+    // See if this candidate is more preferable then the current one if it's the
+    // same family. Or if the current family is IPv4 already so we could safely
+    // ignore all IPv6 ones. WebRTC bug 4269.
+    // http://code.google.com/p/webrtc/issues/detail?id=4269
+    if ((preference <= current_preference && current_family == family) ||
+        (current_family == AF_INET && family == AF_INET6)) {
+      continue;
+    }
+    current_preference = preference;
+    current_family = family;
+    const rtc::SocketAddress& candidate_addr =
+        jsep_candidate->candidate().address();
+    port = candidate_addr.port();
+    ip = candidate_addr.ipaddr().ToString();
+    hostname = candidate_addr.hostname();
+  }
+  rtc::SocketAddress connection_addr(ip, port);
+  if (rtc::IPIsUnspec(connection_addr.ipaddr()) && !hostname.empty()) {
+    // When a hostname candidate becomes the (default) connection address,
+    // we use the dummy address 0.0.0.0 and port 9 in the c= and the m= lines.
+    //
+    // We have observed in deployment that with a FQDN in a c= line, SDP parsing
+    // could fail in other JSEP implementations. We note that the wildcard
+    // addresses (0.0.0.0 or ::) with port 9 are given the exception as the
+    // connection address that will not result in an ICE mismatch
+    // (draft-ietf-mmusic-ice-sip-sdp). Also, 0.0.0.0 or :: can be used as the
+    // connection address in the initial offer or answer with trickle ICE
+    // if the offerer or answerer does not want to include the host IP address
+    // (draft-ietf-mmusic-trickle-ice-sip), and in particular 0.0.0.0 has been
+    // widely deployed for this use without outstanding compatibility issues.
+    // Combining the above considerations, we use 0.0.0.0 with port 9 to
+    // populate the c= and the m= lines. See `BuildMediaDescription` in
+    // webrtc_sdp.cc for the SDP generation with
+    // `media_desc->connection_address()`.
+    connection_addr = rtc::SocketAddress(kDummyAddress, kDummyPort);
+  }
+  media_desc->set_connection_address(connection_addr);
+}
+
+}  // namespace
+
+const int JsepSessionDescription::kDefaultVideoCodecId = 100;
+const char JsepSessionDescription::kDefaultVideoCodecName[] = "VP8";
+
+// TODO(steveanton): Remove this default implementation once Chromium has been
+// updated.
+SdpType SessionDescriptionInterface::GetType() const {
+  absl::optional<SdpType> maybe_type = SdpTypeFromString(type());
+  if (maybe_type) {
+    return *maybe_type;
+  } else {
+    RTC_LOG(LS_WARNING) << "Default implementation of "
+                           "SessionDescriptionInterface::GetType does not "
+                           "recognize the result from type(), returning "
+                           "kOffer.";
+    return SdpType::kOffer;
+  }
+}
+
+SessionDescriptionInterface* CreateSessionDescription(const std::string& type,
+                                                      const std::string& sdp,
+                                                      SdpParseError* error) {
+  absl::optional<SdpType> maybe_type = SdpTypeFromString(type);
+  if (!maybe_type) {
+    return nullptr;
+  }
+
+  return CreateSessionDescription(*maybe_type, sdp, error).release();
+}
+
+std::unique_ptr<SessionDescriptionInterface> CreateSessionDescription(
+    SdpType type,
+    const std::string& sdp) {
+  return CreateSessionDescription(type, sdp, nullptr);
+}
+
+std::unique_ptr<SessionDescriptionInterface> CreateSessionDescription(
+    SdpType type,
+    const std::string& sdp,
+    SdpParseError* error_out) {
+  auto jsep_desc = std::make_unique<JsepSessionDescription>(type);
+  if (type != SdpType::kRollback) {
+    if (!SdpDeserialize(sdp, jsep_desc.get(), error_out)) {
+      return nullptr;
+    }
+  }
+  return std::move(jsep_desc);
+}
+
+std::unique_ptr<SessionDescriptionInterface> CreateSessionDescription(
+    SdpType type,
+    const std::string& session_id,
+    const std::string& session_version,
+    std::unique_ptr<cricket::SessionDescription> description) {
+  auto jsep_description = std::make_unique<JsepSessionDescription>(type);
+  bool initialize_success = jsep_description->Initialize(
+      std::move(description), session_id, session_version);
+  RTC_DCHECK(initialize_success);
+  return std::move(jsep_description);
+}
+
+JsepSessionDescription::JsepSessionDescription(SdpType type) : type_(type) {}
+
+JsepSessionDescription::JsepSessionDescription(const std::string& type) {
+  absl::optional<SdpType> maybe_type = SdpTypeFromString(type);
+  if (maybe_type) {
+    type_ = *maybe_type;
+  } else {
+    RTC_LOG(LS_WARNING)
+        << "JsepSessionDescription constructed with invalid type string: "
+        << type << ". Assuming it is an offer.";
+    type_ = SdpType::kOffer;
+  }
+}
+
+JsepSessionDescription::JsepSessionDescription(
+    SdpType type,
+    std::unique_ptr<cricket::SessionDescription> description,
+    absl::string_view session_id,
+    absl::string_view session_version)
+    : description_(std::move(description)),
+      session_id_(session_id),
+      session_version_(session_version),
+      type_(type) {
+  RTC_DCHECK(description_);
+  candidate_collection_.resize(number_of_mediasections());
+}
+
+JsepSessionDescription::~JsepSessionDescription() {}
+
+bool JsepSessionDescription::Initialize(
+    std::unique_ptr<cricket::SessionDescription> description,
+    const std::string& session_id,
+    const std::string& session_version) {
+  if (!description)
+    return false;
+
+  session_id_ = session_id;
+  session_version_ = session_version;
+  description_ = std::move(description);
+  candidate_collection_.resize(number_of_mediasections());
+  return true;
+}
+
+std::unique_ptr<SessionDescriptionInterface> JsepSessionDescription::Clone()
+    const {
+  auto new_description = std::make_unique<JsepSessionDescription>(type_);
+  new_description->session_id_ = session_id_;
+  new_description->session_version_ = session_version_;
+  if (description_) {
+    new_description->description_ = description_->Clone();
+  }
+  for (const auto& collection : candidate_collection_) {
+    new_description->candidate_collection_.push_back(collection.Clone());
+  }
+  return new_description;
+}
+
+bool JsepSessionDescription::AddCandidate(
+    const IceCandidateInterface* candidate) {
+  if (!candidate)
+    return false;
+  size_t mediasection_index = 0;
+  if (!GetMediasectionIndex(candidate, &mediasection_index)) {
+    return false;
+  }
+  if (mediasection_index >= number_of_mediasections())
+    return false;
+  const std::string& content_name =
+      description_->contents()[mediasection_index].name;
+  const cricket::TransportInfo* transport_info =
+      description_->GetTransportInfoByName(content_name);
+  if (!transport_info) {
+    return false;
+  }
+
+  cricket::Candidate updated_candidate = candidate->candidate();
+  if (updated_candidate.username().empty()) {
+    updated_candidate.set_username(transport_info->description.ice_ufrag);
+  }
+  if (updated_candidate.password().empty()) {
+    updated_candidate.set_password(transport_info->description.ice_pwd);
+  }
+
+  std::unique_ptr<JsepIceCandidate> updated_candidate_wrapper(
+      new JsepIceCandidate(candidate->sdp_mid(),
+                           static_cast<int>(mediasection_index),
+                           updated_candidate));
+  if (!candidate_collection_[mediasection_index].HasCandidate(
+          updated_candidate_wrapper.get())) {
+    candidate_collection_[mediasection_index].add(
+        updated_candidate_wrapper.release());
+    UpdateConnectionAddress(
+        candidate_collection_[mediasection_index],
+        description_->contents()[mediasection_index].media_description());
+  }
+
+  return true;
+}
+
+size_t JsepSessionDescription::RemoveCandidates(
+    const std::vector<cricket::Candidate>& candidates) {
+  size_t num_removed = 0;
+  for (auto& candidate : candidates) {
+    int mediasection_index = GetMediasectionIndex(candidate);
+    if (mediasection_index < 0) {
+      // Not found.
+      continue;
+    }
+    num_removed += candidate_collection_[mediasection_index].remove(candidate);
+    UpdateConnectionAddress(
+        candidate_collection_[mediasection_index],
+        description_->contents()[mediasection_index].media_description());
+  }
+  return num_removed;
+}
+
+size_t JsepSessionDescription::number_of_mediasections() const {
+  if (!description_)
+    return 0;
+  return description_->contents().size();
+}
+
+const IceCandidateCollection* JsepSessionDescription::candidates(
+    size_t mediasection_index) const {
+  if (mediasection_index >= candidate_collection_.size())
+    return NULL;
+  return &candidate_collection_[mediasection_index];
+}
+
+bool JsepSessionDescription::ToString(std::string* out) const {
+  if (!description_ || !out) {
+    return false;
+  }
+  *out = SdpSerialize(*this);
+  return !out->empty();
+}
+
+bool JsepSessionDescription::GetMediasectionIndex(
+    const IceCandidateInterface* candidate,
+    size_t* index) {
+  if (!candidate || !index) {
+    return false;
+  }
+
+  // If the candidate has no valid mline index or sdp_mid, it is impossible
+  // to find a match.
+  if (candidate->sdp_mid().empty() &&
+      (candidate->sdp_mline_index() < 0 ||
+       static_cast<size_t>(candidate->sdp_mline_index()) >=
+           description_->contents().size())) {
+    return false;
+  }
+
+  if (candidate->sdp_mline_index() >= 0)
+    *index = static_cast<size_t>(candidate->sdp_mline_index());
+  if (description_ && !candidate->sdp_mid().empty()) {
+    bool found = false;
+    // Try to match the sdp_mid with content name.
+    for (size_t i = 0; i < description_->contents().size(); ++i) {
+      if (candidate->sdp_mid() == description_->contents().at(i).name) {
+        *index = i;
+        found = true;
+        break;
+      }
+    }
+    if (!found) {
+      // If the sdp_mid is presented but we can't find a match, we consider
+      // this as an error.
+      return false;
+    }
+  }
+  return true;
+}
+
+int JsepSessionDescription::GetMediasectionIndex(
+    const cricket::Candidate& candidate) {
+  // Find the description with a matching transport name of the candidate.
+  const std::string& transport_name = candidate.transport_name();
+  for (size_t i = 0; i < description_->contents().size(); ++i) {
+    if (transport_name == description_->contents().at(i).name) {
+      return static_cast<int>(i);
+    }
+  }
+  return -1;
+}
+
+}  // namespace webrtc