Remove sigslot::has_slots from JsepTransportController

All signals are now connected via slots in other objects.

Bug: webrtc:42222066
Change-Id: I4e6fdea52aa0a0c21ff24698fe33a6263e279e5f
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/417421
Commit-Queue: Harald Alvestrand <hta@webrtc.org>
Reviewed-by: Henrik Boström <hbos@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#45960}
diff --git a/pc/jsep_transport_controller.h b/pc/jsep_transport_controller.h
index 5420a27..bb5b3f2 100644
--- a/pc/jsep_transport_controller.h
+++ b/pc/jsep_transport_controller.h
@@ -62,14 +62,12 @@
 #include "rtc_base/rtc_certificate.h"
 #include "rtc_base/ssl_certificate.h"
 #include "rtc_base/ssl_stream_adapter.h"
-#include "rtc_base/third_party/sigslot/sigslot.h"
 #include "rtc_base/thread.h"
 #include "rtc_base/thread_annotations.h"
 
 namespace webrtc {
 
-class JsepTransportController : public PayloadTypeSuggester,
-                                public sigslot::has_slots<> {
+class JsepTransportController : public PayloadTypeSuggester {
  public:
   // Used when the RtpTransport/DtlsTransport of the m= section is changed
   // because the section is rejected or BUNDLE is enabled.