Delete unneeded includes of deprecated system_wrappers include files.

Deletes left-over includes of trace.h and critical_section_wrapper.h.

BUG=webrtc:7035

Review-Url: https://codereview.webrtc.org/2784873002
Cr-Commit-Position: refs/heads/master@{#17460}
diff --git a/webrtc/modules/video_coding/media_optimization.h b/webrtc/modules/video_coding/media_optimization.h
index bc48300..dcca61b 100644
--- a/webrtc/modules/video_coding/media_optimization.h
+++ b/webrtc/modules/video_coding/media_optimization.h
@@ -14,10 +14,10 @@
 #include <list>
 #include <memory>
 
+#include "webrtc/base/criticalsection.h"
 #include "webrtc/modules/include/module_common_types.h"
 #include "webrtc/modules/video_coding/include/video_coding.h"
 #include "webrtc/modules/video_coding/media_opt_util.h"
-#include "webrtc/system_wrappers/include/critical_section_wrapper.h"
 
 namespace webrtc {