Remove unused critical section includes.

Bug: webrtc:11567
Change-Id: Ic5e43c51ce06c0619adc265d12ad4bef73a9df76
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/179521
Reviewed-by: Tommi <tommi@webrtc.org>
Commit-Queue: Markus Handell <handellm@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#31745}

modules/video_coding/codecs/h264/h264_decoder_impl.cc

@@ -32,7 +32,6 @@ extern "C" {
 #include "common_video/include/video_frame_buffer.h"
 #include "modules/video_coding/codecs/h264/h264_color_space.h"
 #include "rtc_base/checks.h"
-#include "rtc_base/critical_section.h"
 #include "rtc_base/keep_ref_until_done.h"
 #include "rtc_base/logging.h"
 #include "system_wrappers/include/field_trial.h"

modules/video_coding/frame_object.cc

@@ -17,7 +17,6 @@
 #include "api/video/encoded_image.h"
 #include "api/video/video_timing.h"
 #include "rtc_base/checks.h"
-#include "rtc_base/critical_section.h"
 
 namespace webrtc {
 namespace video_coding {

modules/video_coding/receiver.h

@@ -20,7 +20,6 @@
 #include "modules/video_coding/jitter_buffer.h"
 #include "modules/video_coding/packet.h"
 #include "modules/video_coding/timing.h"
-#include "rtc_base/critical_section.h"
 
 namespace webrtc {
 

modules/video_coding/rtp_frame_reference_finder.h

@@ -21,7 +21,6 @@
 #include "modules/include/module_common_types_public.h"
 #include "modules/rtp_rtcp/source/rtp_video_header.h"
 #include "modules/video_coding/codecs/vp9/include/vp9_globals.h"
-#include "rtc_base/critical_section.h"
 #include "rtc_base/numerics/sequence_number_util.h"
 #include "rtc_base/thread_annotations.h"
 

modules/video_coding/video_coding_impl.cc

@@ -16,7 +16,6 @@
 #include "api/video/encoded_image.h"
 #include "modules/video_coding/include/video_codec_interface.h"
 #include "modules/video_coding/timing.h"
-#include "rtc_base/critical_section.h"
 #include "rtc_base/thread_checker.h"
 #include "system_wrappers/include/clock.h"