Revert "Delete test/constants.h"

This reverts commit 389b1672a32f2dd49af6c6ed40e8ddf394b986de.

Reason for revert: Causes failure (and empty result list) in CallPerfTest.PadsToMinTransmitBitrate

Original change's description:
> Delete test/constants.h
>
> It's not possible to use constants.h for all RTP extensions
> after the number of extensions exceeds 14, which is the maximum
> number of one-byte RTP extensions. This is because some extensions
> would have to be assigned a number greater than 14, even if the
> test only involves 14 extensions or less.
>
> For uniformity's sake, this CL also edits some files to use an
> enum as the files involved in this CL, rather than free-floating
> const-ints.
>
> Bug: webrtc:10288
> Change-Id: Ib5e58ad72c4d3756f4c4f6521f140ec59617f3f5
> Reviewed-on: https://webrtc-review.googlesource.com/c/123048
> Commit-Queue: Elad Alon <eladalon@webrtc.org>
> Reviewed-by: Danil Chapovalov <danilchap@webrtc.org>
> Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
> Reviewed-by: Erik Språng <sprang@webrtc.org>
> Cr-Commit-Position: refs/heads/master@{#26728}

TBR=danilchap@webrtc.org,kwiberg@webrtc.org,eladalon@webrtc.org,sprang@webrtc.org

No-Presubmit: True
Bug: webrtc:10288, chromium:933127
Change-Id: If1de0bd8992137c52bf0b877b3cb0a2bafc809d4
Reviewed-on: https://webrtc-review.googlesource.com/c/123381
Commit-Queue: Oleh Prypin <oprypin@webrtc.org>
Reviewed-by: Oleh Prypin <oprypin@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#26744}
diff --git a/audio/audio_send_stream_tests.cc b/audio/audio_send_stream_tests.cc
index 8a83554..55de03d 100644
--- a/audio/audio_send_stream_tests.cc
+++ b/audio/audio_send_stream_tests.cc
@@ -8,11 +8,8 @@
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
-#include <string>
-#include <utility>
-#include <vector>
-
 #include "test/call_test.h"
+#include "test/constants.h"
 #include "test/field_trial.h"
 #include "test/gtest.h"
 #include "test/rtcp_packet_parser.h"
@@ -21,11 +18,6 @@
 namespace test {
 namespace {
 
-enum : int {  // The first valid value is 1.
-  kAudioLevelExtensionId = 1,
-  kTransportSequenceNumberExtensionId,
-};
-
 class AudioSendTest : public SendTest {
  public:
   AudioSendTest() : SendTest(CallTest::kDefaultTimeoutMs) {}
@@ -111,8 +103,8 @@
   class AudioLevelObserver : public AudioSendTest {
    public:
     AudioLevelObserver() : AudioSendTest() {
-      EXPECT_TRUE(parser_->RegisterRtpHeaderExtension(kRtpExtensionAudioLevel,
-                                                      kAudioLevelExtensionId));
+      EXPECT_TRUE(parser_->RegisterRtpHeaderExtension(
+          kRtpExtensionAudioLevel, test::kAudioLevelExtensionId));
     }
 
     Action OnSendRtp(const uint8_t* packet, size_t length) override {
@@ -135,8 +127,8 @@
         AudioSendStream::Config* send_config,
         std::vector<AudioReceiveStream::Config>* receive_configs) override {
       send_config->rtp.extensions.clear();
-      send_config->rtp.extensions.push_back(
-          RtpExtension(RtpExtension::kAudioLevelUri, kAudioLevelExtensionId));
+      send_config->rtp.extensions.push_back(RtpExtension(
+          RtpExtension::kAudioLevelUri, test::kAudioLevelExtensionId));
     }
 
     void PerformTest() override {
diff --git a/audio/test/audio_bwe_integration_test.cc b/audio/test/audio_bwe_integration_test.cc
index 2e3c158..74eaef0 100644
--- a/audio/test/audio_bwe_integration_test.cc
+++ b/audio/test/audio_bwe_integration_test.cc
@@ -23,10 +23,6 @@
 namespace test {
 
 namespace {
-enum : int {  // The first valid value is 1.
-  kTransportSequenceNumberExtensionId = 1,
-};
-
 // Wait a second between stopping sending and stopping receiving audio.
 constexpr int kExtraProcessTimeMs = 1000;
 }  // namespace
diff --git a/modules/rtp_rtcp/source/rtp_sender_audio_unittest.cc b/modules/rtp_rtcp/source/rtp_sender_audio_unittest.cc
index c5ca7f0..7f9d72f 100644
--- a/modules/rtp_rtcp/source/rtp_sender_audio_unittest.cc
+++ b/modules/rtp_rtcp/source/rtp_sender_audio_unittest.cc
@@ -22,10 +22,7 @@
 namespace webrtc {
 
 namespace {
-enum : int {  // The first valid value is 1.
-  kAudioLevelExtensionId = 1,
-};
-
+const int kAudioLevelExtensionId = 9;
 const uint16_t kSeqNum = 33;
 const uint32_t kSsrc = 725242;
 const uint8_t kAudioLevel = 0x5a;
diff --git a/modules/rtp_rtcp/source/rtp_sender_unittest.cc b/modules/rtp_rtcp/source/rtp_sender_unittest.cc
index 0b881f8..714fac7 100644
--- a/modules/rtp_rtcp/source/rtp_sender_unittest.cc
+++ b/modules/rtp_rtcp/source/rtp_sender_unittest.cc
@@ -40,19 +40,16 @@
 namespace webrtc {
 
 namespace {
-enum : int {  // The first valid value is 1.
-  kAbsoluteSendTimeExtensionId = 1,
-  kAudioLevelExtensionId,
-  kGenericDescriptorId,
-  kMidExtensionId,
-  kRepairedRidExtensionId,
-  kRidExtensionId,
-  kTransmissionTimeOffsetExtensionId,
-  kTransportSequenceNumberExtensionId,
-  kVideoRotationExtensionId,
-  kVideoTimingExtensionId,
-};
-
+const int kTransmissionTimeOffsetExtensionId = 1;
+const int kAbsoluteSendTimeExtensionId = 14;
+const int kTransportSequenceNumberExtensionId = 13;
+const int kVideoTimingExtensionId = 12;
+const int kMidExtensionId = 11;
+const int kGenericDescriptorId = 10;
+const int kAudioLevelExtensionId = 9;
+const int kRidExtensionId = 8;
+const int kRepairedRidExtensionId = 7;
+const int kVideoRotationExtensionId = 5;
 const int kPayload = 100;
 const int kRtxPayload = 98;
 const uint32_t kTimestamp = 10;
diff --git a/modules/rtp_rtcp/source/rtp_sender_video_unittest.cc b/modules/rtp_rtcp/source/rtp_sender_video_unittest.cc
index 0cd0572..43eb4ed 100644
--- a/modules/rtp_rtcp/source/rtp_sender_video_unittest.cc
+++ b/modules/rtp_rtcp/source/rtp_sender_video_unittest.cc
@@ -34,16 +34,13 @@
 
 using ::testing::ElementsAre;
 
-enum : int {  // The first valid value is 1.
-  kAbsoluteSendTimeExtensionId = 1,
-  kFrameMarkingExtensionId,
-  kGenericDescriptorId,
-  kTransmissionTimeOffsetExtensionId,
-  kTransportSequenceNumberExtensionId,
-  kVideoRotationExtensionId,
-  kVideoTimingExtensionId,
-};
-
+constexpr int kTransmissionTimeOffsetExtensionId = 1;
+constexpr int kAbsoluteSendTimeExtensionId = 14;
+constexpr int kTransportSequenceNumberExtensionId = 13;
+constexpr int kVideoTimingExtensionId = 12;
+constexpr int kGenericDescriptorId = 10;
+constexpr int kFrameMarkingExtensionId = 6;
+constexpr int kVideoRotationExtensionId = 5;
 constexpr int kPayload = 100;
 constexpr uint32_t kTimestamp = 10;
 constexpr uint16_t kSeqNum = 33;
diff --git a/test/BUILD.gn b/test/BUILD.gn
index 8acc26d..99c5467 100644
--- a/test/BUILD.gn
+++ b/test/BUILD.gn
@@ -656,6 +656,8 @@
   sources = [
     "call_test.cc",
     "call_test.h",
+    "constants.cc",
+    "constants.h",
     "drifting_clock.cc",
     "drifting_clock.h",
     "encoder_settings.cc",
@@ -746,7 +748,6 @@
     "../video",
     "//testing/gtest",
     "//third_party/abseil-cpp/absl/memory",
-    "//third_party/abseil-cpp/absl/types:optional",
   ]
   if (!is_android && !build_with_chromium) {
     deps += [ "../modules/video_capture:video_capture_internal_impl" ]
diff --git a/test/call_test.cc b/test/call_test.cc
index ca0d7bb..57a5d9f 100644
--- a/test/call_test.cc
+++ b/test/call_test.cc
@@ -65,29 +65,6 @@
   });
 }
 
-void CallTest::RegisterRtpExtension(const RtpExtension& extension) {
-  for (const RtpExtension& registered_extension : rtp_extensions_) {
-    if (registered_extension.id == extension.id) {
-      ASSERT_EQ(registered_extension.uri, extension.uri)
-          << "Different URIs associated with ID " << extension.id << ".";
-      ASSERT_EQ(registered_extension.encrypt, extension.encrypt)
-          << "Encryption mismatch associated with ID " << extension.id << ".";
-      return;
-    } else {  // Different IDs.
-      // Different IDs referring to the same extension probably indicate
-      // a mistake in the test.
-      ASSERT_FALSE(registered_extension.uri == extension.uri &&
-                   registered_extension.encrypt == extension.encrypt)
-          << "URI " << extension.uri
-          << (extension.encrypt ? " with " : " without ")
-          << "encryption already registered with a different "
-          << "ID (" << extension.id << " vs. " << registered_extension.id
-          << ").";
-    }
-  }
-  rtp_extensions_.push_back(extension);
-}
-
 void CallTest::RunBaseTest(BaseTest* test) {
   task_queue_.SendTask([this, test]() {
     num_video_streams_ = test->GetNumVideoStreams();
@@ -258,23 +235,25 @@
   video_config->rtp.payload_name = "FAKE";
   video_config->rtp.payload_type = kFakeVideoSendPayloadType;
   video_config->rtp.extmap_allow_mixed = true;
-  AddRtpExtensionByUri(RtpExtension::kTransportSequenceNumberUri,
-                       &video_config->rtp.extensions);
-  AddRtpExtensionByUri(RtpExtension::kVideoContentTypeUri,
-                       &video_config->rtp.extensions);
-  AddRtpExtensionByUri(RtpExtension::kGenericFrameDescriptorUri,
-                       &video_config->rtp.extensions);
+  video_config->rtp.extensions.push_back(
+      RtpExtension(RtpExtension::kTransportSequenceNumberUri,
+                   kTransportSequenceNumberExtensionId));
+  video_config->rtp.extensions.push_back(RtpExtension(
+      RtpExtension::kVideoContentTypeUri, kVideoContentTypeExtensionId));
+  video_config->rtp.extensions.push_back(RtpExtension(
+      RtpExtension::kGenericFrameDescriptorUri, kGenericDescriptorExtensionId));
   if (video_encoder_configs_.empty()) {
     video_encoder_configs_.emplace_back();
     FillEncoderConfiguration(kVideoCodecGeneric, num_video_streams,
                              &video_encoder_configs_.back());
   }
+
   for (size_t i = 0; i < num_video_streams; ++i)
     video_config->rtp.ssrcs.push_back(kVideoSendSsrcs[num_used_ssrcs + i]);
-  AddRtpExtensionByUri(RtpExtension::kVideoRotationUri,
-                       &video_config->rtp.extensions);
-  AddRtpExtensionByUri(RtpExtension::kColorSpaceUri,
-                       &video_config->rtp.extensions);
+  video_config->rtp.extensions.push_back(
+      RtpExtension(RtpExtension::kVideoRotationUri, kVideoRotationExtensionId));
+  video_config->rtp.extensions.push_back(
+      RtpExtension(RtpExtension::kColorSpaceUri, kColorSpaceExtensionId));
 }
 
 void CallTest::CreateAudioAndFecSendConfigs(size_t num_audio_streams,
@@ -687,25 +666,6 @@
   return &flexfec_receive_configs_[0];
 }
 
-absl::optional<RtpExtension> CallTest::GetRtpExtensionByUri(
-    const std::string& uri) const {
-  for (const auto& extension : rtp_extensions_) {
-    if (extension.uri == uri) {
-      return extension;
-    }
-  }
-  return absl::nullopt;
-}
-
-void CallTest::AddRtpExtensionByUri(
-    const std::string& uri,
-    std::vector<RtpExtension>* extensions) const {
-  const absl::optional<RtpExtension> extension = GetRtpExtensionByUri(uri);
-  if (extension) {
-    extensions->push_back(*extension);
-  }
-}
-
 constexpr size_t CallTest::kNumSsrcs;
 const int CallTest::kDefaultWidth;
 const int CallTest::kDefaultHeight;
diff --git a/test/call_test.h b/test/call_test.h
index dbe8e07..fb26051 100644
--- a/test/call_test.h
+++ b/test/call_test.h
@@ -15,7 +15,6 @@
 #include <string>
 #include <vector>
 
-#include "absl/types/optional.h"
 #include "api/test/video/function_video_decoder_factory.h"
 #include "api/test/video/function_video_encoder_factory.h"
 #include "api/video/video_bitrate_allocator_factory.h"
@@ -72,8 +71,6 @@
   static const std::map<uint8_t, MediaType> payload_type_map_;
 
  protected:
-  void RegisterRtpExtension(const RtpExtension& extension);
-
   // RunBaseTest overwrites the audio_state of the send and receive Call configs
   // to simplify test code.
   void RunBaseTest(BaseTest* test);
@@ -219,13 +216,6 @@
   SingleThreadedTaskQueueForTesting task_queue_;
 
  private:
-  absl::optional<RtpExtension> GetRtpExtensionByUri(
-      const std::string& uri) const;
-
-  void AddRtpExtensionByUri(const std::string& uri,
-                            std::vector<RtpExtension>* extensions) const;
-
-  std::vector<RtpExtension> rtp_extensions_;
   rtc::scoped_refptr<AudioProcessing> apm_send_;
   rtc::scoped_refptr<AudioProcessing> apm_recv_;
   rtc::scoped_refptr<TestAudioDeviceModule> fake_send_audio_device_;
diff --git a/test/constants.cc b/test/constants.cc
new file mode 100644
index 0000000..4f33d25
--- /dev/null
+++ b/test/constants.cc
@@ -0,0 +1,27 @@
+/*
+ *  Copyright (c) 2015 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 "test/constants.h"
+
+namespace webrtc {
+namespace test {
+
+const int kAudioLevelExtensionId = 5;
+const int kTOffsetExtensionId = 6;
+const int kAbsSendTimeExtensionId = 7;
+const int kTransportSequenceNumberExtensionId = 8;
+const int kVideoRotationExtensionId = 9;
+const int kVideoContentTypeExtensionId = 10;
+const int kVideoTimingExtensionId = 11;
+const int kGenericDescriptorExtensionId = 12;
+const int kColorSpaceExtensionId = 13;
+
+}  // namespace test
+}  // namespace webrtc
diff --git a/test/constants.h b/test/constants.h
new file mode 100644
index 0000000..b1b87d6
--- /dev/null
+++ b/test/constants.h
@@ -0,0 +1,24 @@
+/*
+ *  Copyright (c) 2015 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.
+ */
+
+namespace webrtc {
+namespace test {
+
+extern const int kAudioLevelExtensionId;
+extern const int kTOffsetExtensionId;
+extern const int kAbsSendTimeExtensionId;
+extern const int kTransportSequenceNumberExtensionId;
+extern const int kVideoRotationExtensionId;
+extern const int kVideoContentTypeExtensionId;
+extern const int kVideoTimingExtensionId;
+extern const int kGenericDescriptorExtensionId;
+extern const int kColorSpaceExtensionId;
+}  // namespace test
+}  // namespace webrtc
diff --git a/test/rtp_rtcp_observer.h b/test/rtp_rtcp_observer.h
index 830c2f1..7cff645 100644
--- a/test/rtp_rtcp_observer.h
+++ b/test/rtp_rtcp_observer.h
@@ -12,7 +12,6 @@
 
 #include <map>
 #include <memory>
-#include <utility>
 #include <vector>
 
 #include "api/test/simulated_network.h"
@@ -22,6 +21,7 @@
 #include "rtc_base/critical_section.h"
 #include "rtc_base/event.h"
 #include "system_wrappers/include/field_trial.h"
+#include "test/constants.h"
 #include "test/direct_transport.h"
 #include "test/gtest.h"
 
@@ -71,7 +71,14 @@
  protected:
   RtpRtcpObserver() : RtpRtcpObserver(0) {}
   explicit RtpRtcpObserver(int event_timeout_ms)
-      : parser_(RtpHeaderParser::Create()), timeout_ms_(event_timeout_ms) {}
+      : parser_(RtpHeaderParser::Create()), timeout_ms_(event_timeout_ms) {
+    parser_->RegisterRtpHeaderExtension(kRtpExtensionTransmissionTimeOffset,
+                                        kTOffsetExtensionId);
+    parser_->RegisterRtpHeaderExtension(kRtpExtensionAbsoluteSendTime,
+                                        kAbsSendTimeExtensionId);
+    parser_->RegisterRtpHeaderExtension(kRtpExtensionTransportSequenceNumber,
+                                        kTransportSequenceNumberExtensionId);
+  }
 
   rtc::Event observation_complete_;
   const std::unique_ptr<RtpHeaderParser> parser_;
diff --git a/test/scenario/video_stream.cc b/test/scenario/video_stream.cc
index 859626e..2f892f0 100644
--- a/test/scenario/video_stream.cc
+++ b/test/scenario/video_stream.cc
@@ -27,13 +27,8 @@
 namespace webrtc {
 namespace test {
 namespace {
-enum : int {  // The first valid value is 1.
-  kTransportSequenceNumberExtensionId = 1,
-  kVideoContentTypeExtensionId,
-  kVideoRotationRtpExtensionId,
-};
-
 constexpr int kDefaultMaxQp = cricket::WebRtcVideoChannel::kDefaultQpMax;
+const int kVideoRotationRtpExtensionId = 4;
 uint8_t CodecTypeToPayloadType(VideoCodecType codec_type) {
   switch (codec_type) {
     case VideoCodecType::kVideoCodecGeneric:
diff --git a/video/end_to_end_tests/bandwidth_tests.cc b/video/end_to_end_tests/bandwidth_tests.cc
index e7550a4..17bb985 100644
--- a/video/end_to_end_tests/bandwidth_tests.cc
+++ b/video/end_to_end_tests/bandwidth_tests.cc
@@ -26,11 +26,6 @@
 #include "test/video_encoder_proxy_factory.h"
 
 namespace webrtc {
-namespace {
-enum : int {  // The first valid value is 1.
-  kAbsSendTimeExtensionId = 1,
-};
-}  // namespace
 
 class BandwidthEndToEndTest : public test::CallTest {
  public:
@@ -47,8 +42,8 @@
         std::vector<VideoReceiveStream::Config>* receive_configs,
         VideoEncoderConfig* encoder_config) override {
       send_config->rtp.extensions.clear();
-      send_config->rtp.extensions.push_back(
-          RtpExtension(RtpExtension::kAbsSendTimeUri, kAbsSendTimeExtensionId));
+      send_config->rtp.extensions.push_back(RtpExtension(
+          RtpExtension::kAbsSendTimeUri, test::kAbsSendTimeExtensionId));
       (*receive_configs)[0].rtp.remb = true;
       (*receive_configs)[0].rtp.transport_cc = false;
     }
@@ -92,8 +87,8 @@
       VideoEncoderConfig* encoder_config) override {
     if (!send_side_bwe_) {
       send_config->rtp.extensions.clear();
-      send_config->rtp.extensions.push_back(
-          RtpExtension(RtpExtension::kAbsSendTimeUri, kAbsSendTimeExtensionId));
+      send_config->rtp.extensions.push_back(RtpExtension(
+          RtpExtension::kAbsSendTimeUri, test::kAbsSendTimeExtensionId));
       (*receive_configs)[0].rtp.remb = true;
       (*receive_configs)[0].rtp.transport_cc = false;
     }
diff --git a/video/end_to_end_tests/codec_tests.cc b/video/end_to_end_tests/codec_tests.cc
index eab9ef7..ed303ec 100644
--- a/video/end_to_end_tests/codec_tests.cc
+++ b/video/end_to_end_tests/codec_tests.cc
@@ -27,22 +27,11 @@
 #include "test/gtest.h"
 
 namespace webrtc {
-namespace {
-enum : int {  // The first valid value is 1.
-  kColorSpaceExtensionId = 1,
-  kVideoRotationExtensionId,
-};
-}  // namespace
 
 class CodecEndToEndTest : public test::CallTest,
                           public testing::WithParamInterface<std::string> {
  public:
-  CodecEndToEndTest() : field_trial_(GetParam()) {
-    RegisterRtpExtension(
-        RtpExtension(RtpExtension::kColorSpaceUri, kColorSpaceExtensionId));
-    RegisterRtpExtension(RtpExtension(RtpExtension::kVideoRotationUri,
-                                      kVideoRotationExtensionId));
-  }
+  CodecEndToEndTest() : field_trial_(GetParam()) {}
 
  private:
   test::ScopedFieldTrials field_trial_;
@@ -235,10 +224,7 @@
 class EndToEndTestH264 : public test::CallTest,
                          public testing::WithParamInterface<std::string> {
  public:
-  EndToEndTestH264() : field_trial_(GetParam()) {
-    RegisterRtpExtension(RtpExtension(RtpExtension::kVideoRotationUri,
-                                      kVideoRotationExtensionId));
-  }
+  EndToEndTestH264() : field_trial_(GetParam()) {}
 
  private:
   test::ScopedFieldTrials field_trial_;
diff --git a/video/end_to_end_tests/extended_reports_tests.cc b/video/end_to_end_tests/extended_reports_tests.cc
index 955f9cd..5b649d5 100644
--- a/video/end_to_end_tests/extended_reports_tests.cc
+++ b/video/end_to_end_tests/extended_reports_tests.cc
@@ -43,20 +43,8 @@
 #include "test/single_threaded_task_queue.h"
 
 namespace webrtc {
-namespace {
-enum : int {  // The first valid value is 1.
-  kColorSpaceExtensionId = 1,
-  kTransportSequenceNumberExtensionId,
-};
-}  // namespace
 
-class ExtendedReportsEndToEndTest : public test::CallTest {
- public:
-  ExtendedReportsEndToEndTest() {
-    RegisterRtpExtension(RtpExtension(RtpExtension::kTransportSequenceNumberUri,
-                                      kTransportSequenceNumberExtensionId));
-  }
-};
+class ExtendedReportsEndToEndTest : public test::CallTest {};
 
 class RtcpXrObserver : public test::EndToEndTest {
  public:
diff --git a/video/end_to_end_tests/fec_tests.cc b/video/end_to_end_tests/fec_tests.cc
index dbf0b2c..42215d3 100644
--- a/video/end_to_end_tests/fec_tests.cc
+++ b/video/end_to_end_tests/fec_tests.cc
@@ -22,21 +22,10 @@
 #include "test/rtcp_packet_parser.h"
 
 namespace webrtc {
-namespace {
-enum : int {  // The first valid value is 1.
-  kTransportSequenceNumberExtensionId = 1,
-  kVideoRotationExtensionId,
-};
-}  // namespace
 
 class FecEndToEndTest : public test::CallTest {
  public:
-  FecEndToEndTest() {
-    RegisterRtpExtension(RtpExtension(RtpExtension::kTransportSequenceNumberUri,
-                                      kTransportSequenceNumberExtensionId));
-    RegisterRtpExtension(RtpExtension(RtpExtension::kVideoRotationUri,
-                                      kVideoRotationExtensionId));
-  }
+  FecEndToEndTest() = default;
 };
 
 TEST_F(FecEndToEndTest, ReceivesUlpfec) {
diff --git a/video/end_to_end_tests/frame_encryption_tests.cc b/video/end_to_end_tests/frame_encryption_tests.cc
index 85ad7dd..98b3a4b 100644
--- a/video/end_to_end_tests/frame_encryption_tests.cc
+++ b/video/end_to_end_tests/frame_encryption_tests.cc
@@ -17,18 +17,10 @@
 #include "test/gtest.h"
 
 namespace webrtc {
-namespace {
-enum : int {  // The first valid value is 1.
-  kGenericDescriptorExtensionId = 1,
-};
-}  // namespace
 
 class FrameEncryptionEndToEndTest : public test::CallTest {
  public:
-  FrameEncryptionEndToEndTest() {
-    RegisterRtpExtension(RtpExtension(RtpExtension::kGenericFrameDescriptorUri,
-                                      kGenericDescriptorExtensionId));
-  }
+  FrameEncryptionEndToEndTest() = default;
 
  private:
   // GenericDescriptor is required for FrameEncryption to work.
diff --git a/video/end_to_end_tests/histogram_tests.cc b/video/end_to_end_tests/histogram_tests.cc
index ef435b4..312924c 100644
--- a/video/end_to_end_tests/histogram_tests.cc
+++ b/video/end_to_end_tests/histogram_tests.cc
@@ -16,22 +16,8 @@
 #include "test/gtest.h"
 
 namespace webrtc {
-namespace {
-enum : int {  // The first valid value is 1.
-  kTransportSequenceNumberExtensionId = 1,
-  kVideoContentTypeExtensionId,
-};
-}  // namespace
 
 class HistogramTest : public test::CallTest {
- public:
-  HistogramTest() {
-    RegisterRtpExtension(RtpExtension(RtpExtension::kTransportSequenceNumberUri,
-                                      kTransportSequenceNumberExtensionId));
-    RegisterRtpExtension(RtpExtension(RtpExtension::kVideoContentTypeUri,
-                                      kVideoContentTypeExtensionId));
-  }
-
  protected:
   void VerifyHistogramStats(bool use_rtx, bool use_fec, bool screenshare);
 };
diff --git a/video/end_to_end_tests/probing_tests.cc b/video/end_to_end_tests/probing_tests.cc
index dba3c3e..80c9ebd 100644
--- a/video/end_to_end_tests/probing_tests.cc
+++ b/video/end_to_end_tests/probing_tests.cc
@@ -15,21 +15,9 @@
 #include "test/call_test.h"
 #include "test/field_trial.h"
 #include "test/gtest.h"
-
 namespace webrtc {
-namespace {
-enum : int {  // The first valid value is 1.
-  kTransportSequenceNumberExtensionId = 1,
-};
-}  // namespace
 
-class ProbingEndToEndTest : public test::CallTest {
- public:
-  ProbingEndToEndTest() {
-    RegisterRtpExtension(RtpExtension(RtpExtension::kTransportSequenceNumberUri,
-                                      kTransportSequenceNumberExtensionId));
-  }
-};
+class ProbingEndToEndTest : public test::CallTest {};
 
 class ProbingTest : public test::EndToEndTest {
  public:
diff --git a/video/end_to_end_tests/retransmission_tests.cc b/video/end_to_end_tests/retransmission_tests.cc
index 49c3fb4..7d31aed 100644
--- a/video/end_to_end_tests/retransmission_tests.cc
+++ b/video/end_to_end_tests/retransmission_tests.cc
@@ -21,18 +21,9 @@
 #include "test/rtcp_packet_parser.h"
 
 namespace webrtc {
-namespace {
-enum : int {  // The first valid value is 1.
-  kVideoRotationExtensionId = 1,
-};
-}  // namespace
-
 class RetransmissionEndToEndTest : public test::CallTest {
  public:
-  RetransmissionEndToEndTest() {
-    RegisterRtpExtension(RtpExtension(RtpExtension::kVideoRotationUri,
-                                      kVideoRotationExtensionId));
-  }
+  RetransmissionEndToEndTest() = default;
 
  protected:
   void DecodesRetransmittedFrame(bool enable_rtx, bool enable_red);
diff --git a/video/end_to_end_tests/rtp_rtcp_tests.cc b/video/end_to_end_tests/rtp_rtcp_tests.cc
index d89a024..bef15d2 100644
--- a/video/end_to_end_tests/rtp_rtcp_tests.cc
+++ b/video/end_to_end_tests/rtp_rtcp_tests.cc
@@ -18,11 +18,6 @@
 #include "test/rtcp_packet_parser.h"
 
 namespace webrtc {
-namespace {
-enum : int {  // The first valid value is 1.
-  kTransportSequenceNumberExtensionId = 1,
-};
-}  // namespace
 
 class RtpRtcpEndToEndTest : public test::CallTest {
  protected:
@@ -535,7 +530,7 @@
     flexfec_receive_config.transport_cc = true;
     flexfec_receive_config.rtp_header_extensions.emplace_back(
         RtpExtension::kTransportSequenceNumberUri,
-        kTransportSequenceNumberExtensionId);
+        test::kTransportSequenceNumberExtensionId);
     flexfec_receive_configs_.push_back(flexfec_receive_config);
 
     CreateFlexfecStreams();
diff --git a/video/end_to_end_tests/stats_tests.cc b/video/end_to_end_tests/stats_tests.cc
index bad04b4..53b181a 100644
--- a/video/end_to_end_tests/stats_tests.cc
+++ b/video/end_to_end_tests/stats_tests.cc
@@ -24,19 +24,7 @@
 #include "test/rtcp_packet_parser.h"
 
 namespace webrtc {
-namespace {
-enum : int {  // The first valid value is 1.
-  kVideoContentTypeExtensionId = 1,
-};
-}  // namespace
-
-class StatsEndToEndTest : public test::CallTest {
- public:
-  StatsEndToEndTest() {
-    RegisterRtpExtension(RtpExtension(RtpExtension::kVideoContentTypeUri,
-                                      kVideoContentTypeExtensionId));
-  }
-};
+class StatsEndToEndTest : public test::CallTest {};
 
 TEST_F(StatsEndToEndTest, GetStats) {
   static const int kStartBitrateBps = 3000000;
diff --git a/video/end_to_end_tests/transport_feedback_tests.cc b/video/end_to_end_tests/transport_feedback_tests.cc
index b607bf6..9aacd9a 100644
--- a/video/end_to_end_tests/transport_feedback_tests.cc
+++ b/video/end_to_end_tests/transport_feedback_tests.cc
@@ -21,21 +21,12 @@
 #include "video/end_to_end_tests/multi_stream_tester.h"
 
 namespace webrtc {
-namespace {
-enum : int {  // The first valid value is 1.
-  kTransportSequenceNumberExtensionId = 1,
-};
-}  // namespace
 
-class TransportFeedbackEndToEndTest : public test::CallTest {
- public:
-  TransportFeedbackEndToEndTest() {
-    RegisterRtpExtension(RtpExtension(RtpExtension::kTransportSequenceNumberUri,
-                                      kTransportSequenceNumberExtensionId));
-  }
-};
+class TransportFeedbackEndToEndTest : public test::CallTest {};
 
 TEST_F(TransportFeedbackEndToEndTest, AssignsTransportSequenceNumbers) {
+  static const int kExtensionId = 5;
+
   class RtpExtensionHeaderObserver : public test::DirectTransport {
    public:
     RtpExtensionHeaderObserver(
@@ -59,7 +50,7 @@
           retransmit_observed_(false),
           started_(false) {
       parser_->RegisterRtpHeaderExtension(kRtpExtensionTransportSequenceNumber,
-                                          kTransportSequenceNumberExtensionId);
+                                          kExtensionId);
     }
     virtual ~RtpExtensionHeaderObserver() {}
 
@@ -183,9 +174,8 @@
         VideoEncoderConfig* encoder_config,
         test::FrameGeneratorCapturer** frame_generator) override {
       send_config->rtp.extensions.clear();
-      send_config->rtp.extensions.push_back(
-          RtpExtension(RtpExtension::kTransportSequenceNumberUri,
-                       kTransportSequenceNumberExtensionId));
+      send_config->rtp.extensions.push_back(RtpExtension(
+          RtpExtension::kTransportSequenceNumberUri, kExtensionId));
 
       // Force some padding to be sent. Note that since we do send media
       // packets we can not guarantee that a padding only packet is sent.
@@ -211,9 +201,8 @@
         VideoReceiveStream::Config* receive_config) override {
       receive_config->rtp.nack.rtp_history_ms = kNackRtpHistoryMs;
       receive_config->rtp.extensions.clear();
-      receive_config->rtp.extensions.push_back(
-          RtpExtension(RtpExtension::kTransportSequenceNumberUri,
-                       kTransportSequenceNumberExtensionId));
+      receive_config->rtp.extensions.push_back(RtpExtension(
+          RtpExtension::kTransportSequenceNumberUri, kExtensionId));
       receive_config->renderer = &fake_renderer_;
     }
 
@@ -302,14 +291,14 @@
       std::vector<AudioReceiveStream::Config>* receive_configs) override {
     send_config->rtp.extensions.clear();
     send_config->rtp.extensions.push_back(
-        RtpExtension(RtpExtension::kTransportSequenceNumberUri,
-                     kTransportSequenceNumberExtensionId));
+        RtpExtension(RtpExtension::kTransportSequenceNumberUri, kExtensionId));
     (*receive_configs)[0].rtp.extensions.clear();
     (*receive_configs)[0].rtp.extensions = send_config->rtp.extensions;
     (*receive_configs)[0].rtp.transport_cc = feedback_enabled_;
   }
 
  private:
+  static const int kExtensionId = 5;
   const bool feedback_enabled_;
   const size_t num_video_streams_;
   const size_t num_audio_streams_;
@@ -437,6 +426,7 @@
 
 TEST_F(TransportFeedbackEndToEndTest, TransportSeqNumOnAudioAndVideo) {
   test::ScopedFieldTrials field_trials("WebRTC-Audio-SendSideBwe/Enabled/");
+  static constexpr int kExtensionId = 8;
   static constexpr size_t kMinPacketsToWaitFor = 50;
   class TransportSequenceNumberTest : public test::EndToEndTest {
    public:
@@ -445,7 +435,7 @@
           video_observed_(false),
           audio_observed_(false) {
       parser_->RegisterRtpHeaderExtension(kRtpExtensionTransportSequenceNumber,
-                                          kTransportSequenceNumberExtensionId);
+                                          kExtensionId);
     }
 
     size_t GetNumVideoStreams() const override { return 1; }
@@ -455,9 +445,8 @@
         AudioSendStream::Config* send_config,
         std::vector<AudioReceiveStream::Config>* receive_configs) override {
       send_config->rtp.extensions.clear();
-      send_config->rtp.extensions.push_back(
-          RtpExtension(RtpExtension::kTransportSequenceNumberUri,
-                       kTransportSequenceNumberExtensionId));
+      send_config->rtp.extensions.push_back(RtpExtension(
+          RtpExtension::kTransportSequenceNumberUri, kExtensionId));
       (*receive_configs)[0].rtp.extensions.clear();
       (*receive_configs)[0].rtp.extensions = send_config->rtp.extensions;
     }
diff --git a/video/video_quality_test.cc b/video/video_quality_test.cc
index 4941827..ad3224d 100644
--- a/video/video_quality_test.cc
+++ b/video/video_quality_test.cc
@@ -47,14 +47,6 @@
 namespace webrtc {
 
 namespace {
-enum : int {  // The first valid value is 1.
-  kAbsSendTimeExtensionId = 1,
-  kGenericFrameDescriptorExtensionId,
-  kTransportSequenceNumberExtensionId,
-  kVideoContentTypeExtensionId,
-  kVideoTimingExtensionId,
-};
-
 constexpr char kSyncGroup[] = "av_sync";
 constexpr int kOpusMinBitrateBps = 6000;
 constexpr int kOpusBitrateFbBps = 32000;
@@ -718,10 +710,10 @@
     if (params_.call.send_side_bwe) {
       video_send_configs_[video_idx].rtp.extensions.emplace_back(
           RtpExtension::kTransportSequenceNumberUri,
-          kTransportSequenceNumberExtensionId);
+          test::kTransportSequenceNumberExtensionId);
     } else {
       video_send_configs_[video_idx].rtp.extensions.emplace_back(
-          RtpExtension::kAbsSendTimeUri, kAbsSendTimeExtensionId);
+          RtpExtension::kAbsSendTimeUri, test::kAbsSendTimeExtensionId);
     }
 
     if (params_.call.generic_descriptor) {
@@ -732,13 +724,13 @@
 
       video_send_configs_[video_idx].rtp.extensions.emplace_back(
           RtpExtension::kGenericFrameDescriptorUri,
-          kGenericFrameDescriptorExtensionId);
+          test::kGenericDescriptorExtensionId);
     }
 
     video_send_configs_[video_idx].rtp.extensions.emplace_back(
-        RtpExtension::kVideoContentTypeUri, kVideoContentTypeExtensionId);
+        RtpExtension::kVideoContentTypeUri, test::kVideoContentTypeExtensionId);
     video_send_configs_[video_idx].rtp.extensions.emplace_back(
-        RtpExtension::kVideoTimingUri, kVideoTimingExtensionId);
+        RtpExtension::kVideoTimingUri, test::kVideoTimingExtensionId);
 
     video_encoder_configs_[video_idx].video_format.name =
         params_.video[video_idx].codec;
@@ -886,10 +878,10 @@
     if (params_.call.send_side_bwe) {
       GetFlexFecConfig()->rtp_header_extensions.push_back(
           RtpExtension(RtpExtension::kTransportSequenceNumberUri,
-                       kTransportSequenceNumberExtensionId));
+                       test::kTransportSequenceNumberExtensionId));
     } else {
-      GetFlexFecConfig()->rtp_header_extensions.push_back(
-          RtpExtension(RtpExtension::kAbsSendTimeUri, kAbsSendTimeExtensionId));
+      GetFlexFecConfig()->rtp_header_extensions.push_back(RtpExtension(
+          RtpExtension::kAbsSendTimeUri, test::kAbsSendTimeExtensionId));
     }
   }
 
@@ -927,10 +919,10 @@
     if (params_.call.send_side_bwe) {
       thumbnail_send_config.rtp.extensions.push_back(
           RtpExtension(RtpExtension::kTransportSequenceNumberUri,
-                       kTransportSequenceNumberExtensionId));
+                       test::kTransportSequenceNumberExtensionId));
     } else {
-      thumbnail_send_config.rtp.extensions.push_back(
-          RtpExtension(RtpExtension::kAbsSendTimeUri, kAbsSendTimeExtensionId));
+      thumbnail_send_config.rtp.extensions.push_back(RtpExtension(
+          RtpExtension::kAbsSendTimeUri, test::kAbsSendTimeExtensionId));
     }
 
     VideoEncoderConfig thumbnail_encoder_config;
@@ -1362,7 +1354,7 @@
   if (params_.call.send_side_bwe) {
     audio_send_config.rtp.extensions.push_back(
         webrtc::RtpExtension(webrtc::RtpExtension::kTransportSequenceNumberUri,
-                             kTransportSequenceNumberExtensionId));
+                             test::kTransportSequenceNumberExtensionId));
     audio_send_config.min_bitrate_bps = kOpusMinBitrateBps;
     audio_send_config.max_bitrate_bps = kOpusBitrateFbBps;
     audio_send_config.send_codec_spec->transport_cc_enabled = true;
diff --git a/video/video_send_stream_tests.cc b/video/video_send_stream_tests.cc
index 0beefec..057fd95 100644
--- a/video/video_send_stream_tests.cc
+++ b/video/video_send_stream_tests.cc
@@ -73,15 +73,6 @@
 }  // namespace test
 
 namespace {
-enum : int {  // The first valid value is 1.
-  kAbsSendTimeExtensionId = 1,
-  kTimestampOffsetExtensionId,
-  kTransportSequenceNumberExtensionId,
-  kVideoContentTypeExtensionId,
-  kVideoRotationExtensionId,
-  kVideoTimingExtensionId,
-};
-
 constexpr int64_t kRtcpIntervalMs = 1000;
 
 enum VideoFormat {
@@ -93,12 +84,6 @@
 VideoFrame CreateVideoFrame(int width, int height, uint8_t data);
 
 class VideoSendStreamTest : public test::CallTest {
- public:
-  VideoSendStreamTest() {
-    RegisterRtpExtension(RtpExtension(RtpExtension::kTransportSequenceNumberUri,
-                                      kTransportSequenceNumberExtensionId));
-  }
-
  protected:
   void TestNackRetransmission(uint32_t retransmit_ssrc,
                               uint8_t retransmit_payload_type);
@@ -178,7 +163,7 @@
    public:
     AbsoluteSendTimeObserver() : SendTest(kDefaultTimeoutMs) {
       EXPECT_TRUE(parser_->RegisterRtpHeaderExtension(
-          kRtpExtensionAbsoluteSendTime, kAbsSendTimeExtensionId));
+          kRtpExtensionAbsoluteSendTime, test::kAbsSendTimeExtensionId));
     }
 
     Action OnSendRtp(const uint8_t* packet, size_t length) override {
@@ -208,8 +193,8 @@
         std::vector<VideoReceiveStream::Config>* receive_configs,
         VideoEncoderConfig* encoder_config) override {
       send_config->rtp.extensions.clear();
-      send_config->rtp.extensions.push_back(
-          RtpExtension(RtpExtension::kAbsSendTimeUri, kAbsSendTimeExtensionId));
+      send_config->rtp.extensions.push_back(RtpExtension(
+          RtpExtension::kAbsSendTimeUri, test::kAbsSendTimeExtensionId));
     }
 
     void PerformTest() override {
@@ -230,7 +215,7 @@
                 Clock::GetRealTimeClock(), kEncodeDelayMs);
           }) {
       EXPECT_TRUE(parser_->RegisterRtpHeaderExtension(
-          kRtpExtensionTransmissionTimeOffset, kTimestampOffsetExtensionId));
+          kRtpExtensionTransmissionTimeOffset, test::kTOffsetExtensionId));
     }
 
    private:
@@ -254,7 +239,7 @@
       send_config->encoder_settings.encoder_factory = &encoder_factory_;
       send_config->rtp.extensions.clear();
       send_config->rtp.extensions.push_back(RtpExtension(
-          RtpExtension::kTimestampOffsetUri, kTimestampOffsetExtensionId));
+          RtpExtension::kTimestampOffsetUri, test::kTOffsetExtensionId));
     }
 
     void PerformTest() override {
@@ -268,7 +253,7 @@
 }
 
 TEST_F(VideoSendStreamTest, SupportsTransportWideSequenceNumbers) {
-  static const uint8_t kExtensionId = kTransportSequenceNumberExtensionId;
+  static const uint8_t kExtensionId = test::kTransportSequenceNumberExtensionId;
   class TransportWideSequenceNumberObserver : public test::SendTest {
    public:
     TransportWideSequenceNumberObserver()
@@ -316,7 +301,7 @@
    public:
     VideoRotationObserver() : SendTest(kDefaultTimeoutMs) {
       EXPECT_TRUE(parser_->RegisterRtpHeaderExtension(
-          kRtpExtensionVideoRotation, kVideoRotationExtensionId));
+          kRtpExtensionVideoRotation, test::kVideoRotationExtensionId));
     }
 
     Action OnSendRtp(const uint8_t* packet, size_t length) override {
@@ -337,7 +322,7 @@
         VideoEncoderConfig* encoder_config) override {
       send_config->rtp.extensions.clear();
       send_config->rtp.extensions.push_back(RtpExtension(
-          RtpExtension::kVideoRotationUri, kVideoRotationExtensionId));
+          RtpExtension::kVideoRotationUri, test::kVideoRotationExtensionId));
     }
 
     void OnFrameGeneratorCapturerCreated(
@@ -359,7 +344,7 @@
     VideoContentTypeObserver()
         : SendTest(kDefaultTimeoutMs), first_frame_sent_(false) {
       EXPECT_TRUE(parser_->RegisterRtpHeaderExtension(
-          kRtpExtensionVideoContentType, kVideoContentTypeExtensionId));
+          kRtpExtensionVideoContentType, test::kVideoContentTypeExtensionId));
     }
 
     Action OnSendRtp(const uint8_t* packet, size_t length) override {
@@ -382,8 +367,9 @@
         std::vector<VideoReceiveStream::Config>* receive_configs,
         VideoEncoderConfig* encoder_config) override {
       send_config->rtp.extensions.clear();
-      send_config->rtp.extensions.push_back(RtpExtension(
-          RtpExtension::kVideoContentTypeUri, kVideoContentTypeExtensionId));
+      send_config->rtp.extensions.push_back(
+          RtpExtension(RtpExtension::kVideoContentTypeUri,
+                       test::kVideoContentTypeExtensionId));
       encoder_config->content_type = VideoEncoderConfig::ContentType::kScreen;
     }
 
@@ -403,8 +389,8 @@
    public:
     VideoTimingObserver()
         : SendTest(kDefaultTimeoutMs), first_frame_sent_(false) {
-      EXPECT_TRUE(parser_->RegisterRtpHeaderExtension(kRtpExtensionVideoTiming,
-                                                      kVideoTimingExtensionId));
+      EXPECT_TRUE(parser_->RegisterRtpHeaderExtension(
+          kRtpExtensionVideoTiming, test::kVideoTimingExtensionId));
     }
 
     Action OnSendRtp(const uint8_t* packet, size_t length) override {
@@ -426,8 +412,8 @@
         std::vector<VideoReceiveStream::Config>* receive_configs,
         VideoEncoderConfig* encoder_config) override {
       send_config->rtp.extensions.clear();
-      send_config->rtp.extensions.push_back(
-          RtpExtension(RtpExtension::kVideoTimingUri, kVideoTimingExtensionId));
+      send_config->rtp.extensions.push_back(RtpExtension(
+          RtpExtension::kVideoTimingUri, test::kVideoTimingExtensionId));
     }
 
     void PerformTest() override {
@@ -478,12 +464,7 @@
         expect_ulpfec_(expect_ulpfec),
         sent_media_(false),
         sent_ulpfec_(false),
-        header_extensions_enabled_(header_extensions_enabled) {
-    parser_->RegisterRtpHeaderExtension(kRtpExtensionAbsoluteSendTime,
-                                        kAbsSendTimeExtensionId);
-    parser_->RegisterRtpHeaderExtension(kRtpExtensionTransportSequenceNumber,
-                                        kTransportSequenceNumberExtensionId);
-  }
+        header_extensions_enabled_(header_extensions_enabled) {}
 
   // Some of the test cases are expected to time out and thus we are using
   // a shorter timeout window than the default here.
@@ -583,11 +564,12 @@
         VideoSendStreamTest::kRedPayloadType;
     send_config->rtp.ulpfec.ulpfec_payload_type =
         VideoSendStreamTest::kUlpfecPayloadType;
+    EXPECT_FALSE(send_config->rtp.extensions.empty());
     if (!header_extensions_enabled_) {
       send_config->rtp.extensions.clear();
     } else {
-      send_config->rtp.extensions.push_back(
-          RtpExtension(RtpExtension::kAbsSendTimeUri, kAbsSendTimeExtensionId));
+      send_config->rtp.extensions.push_back(RtpExtension(
+          RtpExtension::kAbsSendTimeUri, test::kAbsSendTimeExtensionId));
     }
     encoder_config->codec_type = PayloadStringToCodecType(payload_name_);
     (*receive_configs)[0].rtp.red_payload_type =
@@ -705,14 +687,7 @@
         sent_media_(false),
         sent_flexfec_(false),
         header_extensions_enabled_(header_extensions_enabled),
-        num_video_streams_(num_video_streams) {
-    parser_->RegisterRtpHeaderExtension(kRtpExtensionAbsoluteSendTime,
-                                        kAbsSendTimeExtensionId);
-    parser_->RegisterRtpHeaderExtension(kRtpExtensionTransmissionTimeOffset,
-                                        kTimestampOffsetExtensionId);
-    parser_->RegisterRtpHeaderExtension(kRtpExtensionTransportSequenceNumber,
-                                        kTransportSequenceNumberExtensionId);
-  }
+        num_video_streams_(num_video_streams) {}
 
   size_t GetNumFlexfecStreams() const override { return 1; }
   size_t GetNumVideoStreams() const override { return num_video_streams_; }
@@ -776,10 +751,10 @@
     send_config->encoder_settings.encoder_factory = encoder_factory_;
     send_config->rtp.payload_name = payload_name_;
     if (header_extensions_enabled_) {
-      send_config->rtp.extensions.push_back(
-          RtpExtension(RtpExtension::kAbsSendTimeUri, kAbsSendTimeExtensionId));
       send_config->rtp.extensions.push_back(RtpExtension(
-          RtpExtension::kTimestampOffsetUri, kTimestampOffsetExtensionId));
+          RtpExtension::kAbsSendTimeUri, test::kAbsSendTimeExtensionId));
+      send_config->rtp.extensions.push_back(RtpExtension(
+          RtpExtension::kTimestampOffsetUri, test::kTOffsetExtensionId));
     } else {
       send_config->rtp.extensions.clear();
     }
@@ -1653,7 +1628,7 @@
 TEST_F(VideoSendStreamTest, ChangingNetworkRoute) {
   static const int kStartBitrateBps = 300000;
   static const int kNewMaxBitrateBps = 1234567;
-  static const uint8_t kExtensionId = kTransportSequenceNumberExtensionId;
+  static const uint8_t kExtensionId = test::kTransportSequenceNumberExtensionId;
   class ChangingNetworkRouteTest : public test::EndToEndTest {
    public:
     explicit ChangingNetworkRouteTest(