[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/modules/video_coding/session_info.cc b/modules/video_coding/session_info.cc
index 0887109..c37aaf7 100644
--- a/modules/video_coding/session_info.cc
+++ b/modules/video_coding/session_info.cc
@@ -9,6 +9,17 @@
  */
 
 #include "modules/video_coding/session_info.h"
+
+#include <assert.h>
+#include <string.h>
+#include <vector>
+
+#include "absl/types/variant.h"
+#include "modules/include/module_common_types.h"
+#include "modules/include/module_common_types_public.h"
+#include "modules/rtp_rtcp/source/rtp_video_header.h"
+#include "modules/video_coding/codecs/interface/common_constants.h"
+#include "modules/video_coding/codecs/vp8/include/vp8_globals.h"
 #include "modules/video_coding/jitter_buffer_common.h"
 #include "modules/video_coding/packet.h"
 #include "rtc_base/logging.h"