Delete rtc_base/atomic_ops.h

Bug: webrtc:9305
Change-Id: I3e8b0db03b84b5361d63db31ee23e6db3deabfe4
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/266497
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Commit-Queue: Niels Moller <nisse@webrtc.org>
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#37348}
diff --git a/modules/audio_processing/audio_processing_impl.h b/modules/audio_processing/audio_processing_impl.h
index 974089b..86ecb80 100644
--- a/modules/audio_processing/audio_processing_impl.h
+++ b/modules/audio_processing/audio_processing_impl.h
@@ -13,6 +13,7 @@
 
 #include <stdio.h>
 
+#include <atomic>
 #include <list>
 #include <memory>
 #include <string>
@@ -180,7 +181,7 @@
   };
 
   const std::unique_ptr<ApmDataDumper> data_dumper_;
-  static int instance_count_;
+  static std::atomic<int> instance_count_;
   const bool use_setup_specific_default_aec3_config_;
 
   const bool use_denormal_disabler_;