Injectable audio encoders: Moved audio encoder, factory and builtin factory to api/.

webrtc/api/audio_codecs/audio_encoder.h

Index: webrtc/api/audio_codecs/audio_encoder.h
diff --git a/webrtc/modules/audio_coding/codecs/audio_encoder.h b/webrtc/api/audio_codecs/audio_encoder.h
similarity index 97%
copy from webrtc/modules/audio_coding/codecs/audio_encoder.h
copy to webrtc/api/audio_codecs/audio_encoder.h
index bdbbf2d45b7871cf1ab2eaaf3327e63612d93153..3e810005fd99c8b6e8b8aac6a91df6baf5966694 100644
--- a/webrtc/modules/audio_coding/codecs/audio_encoder.h
+++ b/webrtc/api/audio_codecs/audio_encoder.h
@@ -8,10 +8,12 @@
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
-#ifndef WEBRTC_MODULES_AUDIO_CODING_CODECS_AUDIO_ENCODER_H_
-#define WEBRTC_MODULES_AUDIO_CODING_CODECS_AUDIO_ENCODER_H_
+#ifndef WEBRTC_API_AUDIO_CODECS_AUDIO_ENCODER_H_
+#define WEBRTC_API_AUDIO_CODECS_AUDIO_ENCODER_H_
 
 #include <algorithm>
+#include <memory>
+#include <string>
 #include <vector>
 
 #include "webrtc/base/array_view.h"
@@ -209,4 +211,4 @@ class AudioEncoder {
                                  rtc::Buffer* encoded) = 0;
 };
 }  // namespace webrtc
-#endif  // WEBRTC_MODULES_AUDIO_CODING_CODECS_AUDIO_ENCODER_H_
+#endif  // WEBRTC_API_AUDIO_CODECS_AUDIO_ENCODER_H_