[Cleanup] Add missing #include. Remove useless ones. IWYU part 2.

This is a follow-up to
https://webrtc-review.googlesource.com/c/src/+/106280.
This time the whole code base is covered.
Some files may have not been fixed though, whenever the IWYU tool
was breaking the build.

Bug: webrtc:8311
Change-Id: I2c31f552a87e887d33931d46e87b6208b1e483ef
Reviewed-on: https://webrtc-review.googlesource.com/c/111965
Commit-Queue: Yves Gerey <yvesg@google.com>
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#25830}
diff --git a/media/sctp/sctptransport_unittest.cc b/media/sctp/sctptransport_unittest.cc
index 75c2796..c63bde8 100644
--- a/media/sctp/sctptransport_unittest.cc
+++ b/media/sctp/sctptransport_unittest.cc
@@ -8,23 +8,21 @@
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
-#include <errno.h>
-#include <stdarg.h>
 #include <stdio.h>
-
+#include <string.h>
+#include <algorithm>
 #include <memory>
 #include <string>
 #include <vector>
 
 #include "media/sctp/sctptransport.h"
 #include "p2p/base/fakedtlstransport.h"
-#include "rtc_base/bind.h"
 #include "rtc_base/copyonwritebuffer.h"
-#include "rtc_base/criticalsection.h"
 #include "rtc_base/gunit.h"
-#include "rtc_base/helpers.h"
-#include "rtc_base/ssladapter.h"
+#include "rtc_base/logging.h"
+#include "rtc_base/messagequeue.h"
 #include "rtc_base/thread.h"
+#include "test/gtest.h"
 
 namespace {
 static const int kDefaultTimeout = 10000;  // 10 seconds.