[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/modules/audio_processing/voice_detection_impl.h b/modules/audio_processing/voice_detection_impl.h
index 4b724bd..c438473 100644
--- a/modules/audio_processing/voice_detection_impl.h
+++ b/modules/audio_processing/voice_detection_impl.h
@@ -11,11 +11,13 @@
 #ifndef MODULES_AUDIO_PROCESSING_VOICE_DETECTION_IMPL_H_
 #define MODULES_AUDIO_PROCESSING_VOICE_DETECTION_IMPL_H_
 
+#include <stddef.h>
 #include <memory>
 
 #include "modules/audio_processing/include/audio_processing.h"
 #include "rtc_base/constructormagic.h"
 #include "rtc_base/criticalsection.h"
+#include "rtc_base/thread_annotations.h"
 
 namespace webrtc {
 
@@ -42,6 +44,7 @@
 
  private:
   class Vad;
+
   rtc::CriticalSection* const crit_;
   bool enabled_ RTC_GUARDED_BY(crit_) = false;
   bool stream_has_voice_ RTC_GUARDED_BY(crit_) = false;