[Cleanup] Remove unused swap function.

If the need arises, please use:
  using std::swap;
  swap(a, b);
which falls back to a generic std::swap.

Bug: webrtc:9855
Change-Id: I819839d160fc7ae289310a13e3988cdb3f0b3086
Reviewed-on: https://webrtc-review.googlesource.com/c/104100
Commit-Queue: Yves Gerey <yvesg@webrtc.org>
Reviewed-by: Patrik Höglund <phoglund@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#25084}
diff --git a/api/audio_codecs/audio_format.cc b/api/audio_codecs/audio_format.cc
index 81ed299..bd2d3f2 100644
--- a/api/audio_codecs/audio_format.cc
+++ b/api/audio_codecs/audio_format.cc
@@ -46,14 +46,6 @@
          a.parameters == b.parameters;
 }
 
-void swap(SdpAudioFormat& a, SdpAudioFormat& b) {
-  using std::swap;
-  swap(a.name, b.name);
-  swap(a.clockrate_hz, b.clockrate_hz);
-  swap(a.num_channels, b.num_channels);
-  swap(a.parameters, b.parameters);
-}
-
 AudioCodecInfo::AudioCodecInfo(int sample_rate_hz,
                                size_t num_channels,
                                int bitrate_bps)
diff --git a/api/audio_codecs/audio_format.h b/api/audio_codecs/audio_format.h
index 8d28b4f..5c37005 100644
--- a/api/audio_codecs/audio_format.h
+++ b/api/audio_codecs/audio_format.h
@@ -13,8 +13,6 @@
 
 #include <map>
 #include <string>
-// TODO(yvesg) Fix presubmit check and/or remove unused swap function.
-#include <utility>
 
 #include "absl/strings/string_view.h"
 #include "rtc_base/checks.h"
@@ -54,8 +52,6 @@
   Parameters parameters;
 };
 
-void swap(SdpAudioFormat& a, SdpAudioFormat& b);
-
 // Information about how an audio format is treated by the codec implementation.
 // Contains basic information, such as sample rate and number of channels, which
 // isn't uniformly presented by SDP. Also contains flags indicating support for