Revert "Update includes for webrtc/{base => rtc_base} rename (1/3)"

webrtc/modules/audio_mixer/audio_frame_manipulator.cc

Index: webrtc/modules/audio_mixer/audio_frame_manipulator.cc
diff --git a/webrtc/modules/audio_mixer/audio_frame_manipulator.cc b/webrtc/modules/audio_mixer/audio_frame_manipulator.cc
index 3f16bf7823b147dc6de6921f18445edd9d64b36d..fff79a38cf6b4e68f13e30c43a56e31a49dd1efc 100644
--- a/webrtc/modules/audio_mixer/audio_frame_manipulator.cc
+++ b/webrtc/modules/audio_mixer/audio_frame_manipulator.cc
@@ -8,10 +8,10 @@
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
-#include "webrtc/modules/audio_mixer/audio_frame_manipulator.h"
 #include "webrtc/audio/utility/audio_frame_operations.h"
+#include "webrtc/base/checks.h"
+#include "webrtc/modules/audio_mixer/audio_frame_manipulator.h"
 #include "webrtc/modules/include/module_common_types.h"
-#include "webrtc/rtc_base/checks.h"
 
 namespace webrtc {