[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/video/transport_adapter.h b/video/transport_adapter.h
index 786858b..a47fde3 100644
--- a/video/transport_adapter.h
+++ b/video/transport_adapter.h
@@ -10,6 +10,8 @@
 #ifndef VIDEO_TRANSPORT_ADAPTER_H_
 #define VIDEO_TRANSPORT_ADAPTER_H_
 
+#include <stddef.h>
+#include <stdint.h>
 #include <atomic>
 
 #include "api/call/transport.h"