rtpsender interface: make pure virtual again

after providing default implementations in Chromium tests

BUG=None

Change-Id: I53bf26b3a99416f4005e7df75b9b86dfbf2489cb
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/273100
Commit-Queue: Philipp Hancke <phancke@microsoft.com>
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#37941}
diff --git a/api/BUILD.gn b/api/BUILD.gn
index eca66e5..e9db503 100644
--- a/api/BUILD.gn
+++ b/api/BUILD.gn
@@ -208,7 +208,6 @@
     "peer_connection_interface.h",
     "rtp_receiver_interface.cc",
     "rtp_receiver_interface.h",
-    "rtp_sender_interface.cc",
     "rtp_sender_interface.h",
     "rtp_transceiver_interface.cc",
     "rtp_transceiver_interface.h",
diff --git a/api/rtp_sender_interface.cc b/api/rtp_sender_interface.cc
deleted file mode 100644
index 57a5a10..0000000
--- a/api/rtp_sender_interface.cc
+++ /dev/null
@@ -1,36 +0,0 @@
-/*
- *  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 "api/rtp_sender_interface.h"
-
-namespace webrtc {
-
-void RtpSenderInterface::SetFrameEncryptor(
-    rtc::scoped_refptr<FrameEncryptorInterface> frame_encryptor) {}
-
-rtc::scoped_refptr<FrameEncryptorInterface>
-RtpSenderInterface::GetFrameEncryptor() const {
-  return nullptr;
-}
-
-std::vector<RtpEncodingParameters> RtpSenderInterface::init_send_encodings()
-    const {
-  return {};
-}
-
-rtc::scoped_refptr<DtlsTransportInterface> RtpSenderInterface::dtls_transport()
-    const {
-  return nullptr;
-}
-
-void RtpSenderInterface::SetEncoderToPacketizerFrameTransformer(
-    rtc::scoped_refptr<FrameTransformerInterface> frame_transformer) {}
-
-}  // namespace webrtc
diff --git a/api/rtp_sender_interface.h b/api/rtp_sender_interface.h
index 48ea864..500bd25 100644
--- a/api/rtp_sender_interface.h
+++ b/api/rtp_sender_interface.h
@@ -43,8 +43,7 @@
   // The dtlsTransport attribute exposes the DTLS transport on which the
   // media is sent. It may be null.
   // https://w3c.github.io/webrtc-pc/#dom-rtcrtpsender-transport
-  // TODO(https://bugs.webrtc.org/907849) remove default implementation
-  virtual rtc::scoped_refptr<DtlsTransportInterface> dtls_transport() const;
+  virtual rtc::scoped_refptr<DtlsTransportInterface> dtls_transport() const = 0;
 
   // Returns primary SSRC used by this sender for sending media.
   // Returns 0 if not yet determined.
@@ -67,13 +66,13 @@
   // Sets the IDs of the media streams associated with this sender's track.
   // These are signalled in the SDP so that the remote side can associate
   // tracks.
-  virtual void SetStreams(const std::vector<std::string>& stream_ids) {}
+  virtual void SetStreams(const std::vector<std::string>& stream_ids) = 0;
 
   // Returns the list of encoding parameters that will be applied when the SDP
   // local description is set. These initial encoding parameters can be set by
   // PeerConnection::AddTransceiver, and later updated with Get/SetParameters.
   // TODO(orphis): Make it pure virtual once Chrome has updated
-  virtual std::vector<RtpEncodingParameters> init_send_encodings() const;
+  virtual std::vector<RtpEncodingParameters> init_send_encodings() const = 0;
 
   virtual RtpParameters GetParameters() const = 0;
   // Note that only a subset of the parameters can currently be changed. See
@@ -89,20 +88,21 @@
   // using the user provided encryption mechanism regardless of whether SRTP is
   // enabled or not.
   virtual void SetFrameEncryptor(
-      rtc::scoped_refptr<FrameEncryptorInterface> frame_encryptor);
+      rtc::scoped_refptr<FrameEncryptorInterface> frame_encryptor) = 0;
 
   // Returns a pointer to the frame encryptor set previously by the
   // user. This can be used to update the state of the object.
-  virtual rtc::scoped_refptr<FrameEncryptorInterface> GetFrameEncryptor() const;
+  virtual rtc::scoped_refptr<FrameEncryptorInterface> GetFrameEncryptor()
+      const = 0;
 
   virtual void SetEncoderToPacketizerFrameTransformer(
-      rtc::scoped_refptr<FrameTransformerInterface> frame_transformer);
+      rtc::scoped_refptr<FrameTransformerInterface> frame_transformer) = 0;
 
   // Sets a user defined encoder selector.
   // Overrides selector that is (optionally) provided by VideoEncoderFactory.
   virtual void SetEncoderSelector(
       std::unique_ptr<VideoEncoderFactory::EncoderSelectorInterface>
-          encoder_selector) {}
+          encoder_selector) = 0;
 
  protected:
   ~RtpSenderInterface() override = default;
diff --git a/api/test/mock_rtpsender.h b/api/test/mock_rtpsender.h
index e36eec4..e2351f8 100644
--- a/api/test/mock_rtpsender.h
+++ b/api/test/mock_rtpsender.h
@@ -11,6 +11,7 @@
 #ifndef API_TEST_MOCK_RTPSENDER_H_
 #define API_TEST_MOCK_RTPSENDER_H_
 
+#include <memory>
 #include <string>
 #include <vector>
 
@@ -30,10 +31,15 @@
               track,
               (),
               (const, override));
+  MOCK_METHOD(rtc::scoped_refptr<DtlsTransportInterface>,
+              dtls_transport,
+              (),
+              (const override));
   MOCK_METHOD(uint32_t, ssrc, (), (const, override));
   MOCK_METHOD(cricket::MediaType, media_type, (), (const, override));
   MOCK_METHOD(std::string, id, (), (const, override));
   MOCK_METHOD(std::vector<std::string>, stream_ids, (), (const, override));
+  MOCK_METHOD(void, SetStreams, (const std::vector<std::string>&), (override));
   MOCK_METHOD(std::vector<RtpEncodingParameters>,
               init_send_encodings,
               (),
@@ -44,6 +50,22 @@
               GetDtmfSender,
               (),
               (const, override));
+  MOCK_METHOD(void,
+              SetFrameEncryptor,
+              (rtc::scoped_refptr<FrameEncryptorInterface>),
+              (override));
+  MOCK_METHOD(rtc::scoped_refptr<FrameEncryptorInterface>,
+              GetFrameEncryptor,
+              (),
+              (const, override));
+  MOCK_METHOD(void,
+              SetEncoderToPacketizerFrameTransformer,
+              (rtc::scoped_refptr<FrameTransformerInterface>),
+              (override));
+  MOCK_METHOD(void,
+              SetEncoderSelector,
+              (std::unique_ptr<VideoEncoderFactory::EncoderSelectorInterface>),
+              (override));
 };
 
 static_assert(!std::is_abstract_v<rtc::RefCountedObject<MockRtpSender>>, "");