Refactor ring_buffer interface, add a feature and a test.

* Add a RingBuffer typedef.
* Add the ability to force a memcpy by passing a null ptr. In some cases,
  we know we want a memcpy. This allows us to skip a potential
  intermediate memcpy.
* Add a stress test.

Review URL: https://webrtc-codereview.appspot.com/1111004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@3567 4adac7df-926f-26a2-2b94-8c16560cd09d

webrtc/modules/audio_processing/aecm/echo_control_mobile.c

@@ -8,16 +8,16 @@
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
-#include <stdlib.h>
-//#include <string.h>
+#include "webrtc/modules/audio_processing/aecm/include/echo_control_mobile.h"
 
-#include "echo_control_mobile.h"
-#include "aecm_core.h"
-#include "common_audio/signal_processing/include/signal_processing_library.h"
-#include "ring_buffer.h"
 #ifdef AEC_DEBUG
 #include <stdio.h>
 #endif
+#include <stdlib.h>
+
+#include "webrtc/common_audio/signal_processing/include/signal_processing_library.h"
+#include "webrtc/modules/audio_processing/aecm/aecm_core.h"
+#include "webrtc/modules/audio_processing/utility/ring_buffer.h"
 
 #define BUF_SIZE_FRAMES 50 // buffer size (frames)
 // Maximum length of resampled signal. Must be an integer multiple of frames
@@ -66,7 +66,7 @@ typedef struct
     FILE *postCompFile;
 #endif // AEC_DEBUG
     // Structures
-    void *farendBuf;
+    RingBuffer *farendBuf;
 
     int lastError;