[Cleanup] Add missing #include. Remove useless ones.

This CL is the result of running include-what-you-use tool on part
of the code base (audio target and dependencies) plus manual fixes.

bug: webrtc:8311
Change-Id: I277d281ce943c3ecc1bd45fd8d83055931743604
Reviewed-on: https://webrtc-review.googlesource.com/c/106280
Commit-Queue: Yves Gerey <yvesg@google.com>
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Reviewed-by: Patrik Höglund <phoglund@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#25311}
diff --git a/audio/null_audio_poller.h b/audio/null_audio_poller.h
index afb6edb..f91eb7d 100644
--- a/audio/null_audio_poller.h
+++ b/audio/null_audio_poller.h
@@ -11,8 +11,11 @@
 #ifndef AUDIO_NULL_AUDIO_POLLER_H_
 #define AUDIO_NULL_AUDIO_POLLER_H_
 
+#include <stdint.h>
+
 #include "modules/audio_device/include/audio_device_defines.h"
 #include "rtc_base/messagehandler.h"
+#include "rtc_base/messagequeue.h"
 #include "rtc_base/thread_checker.h"
 
 namespace webrtc {