Move swap_queue.h to base/

This will let us use the SwapQueue as a message queue for the event log's output thread. See https://codereview.webrtc.org/1687703002/

Review URL: https://codereview.webrtc.org/1812823007

Cr-Commit-Position: refs/heads/master@{#12113}
diff --git a/webrtc/modules/audio_processing/gain_control_impl.h b/webrtc/modules/audio_processing/gain_control_impl.h
index 6841d5d..a7e7874 100644
--- a/webrtc/modules/audio_processing/gain_control_impl.h
+++ b/webrtc/modules/audio_processing/gain_control_impl.h
@@ -16,8 +16,8 @@
 
 #include "webrtc/base/constructormagic.h"
 #include "webrtc/base/criticalsection.h"
+#include "webrtc/base/swap_queue.h"
 #include "webrtc/base/thread_annotations.h"
-#include "webrtc/common_audio/swap_queue.h"
 #include "webrtc/modules/audio_processing/include/audio_processing.h"
 #include "webrtc/modules/audio_processing/render_queue_item_verifier.h"