Remove RegisterExternal{De,En}coder error codes.

webrtc/modules/video_coding/codec_database.h

Index: webrtc/modules/video_coding/codec_database.h
diff --git a/webrtc/modules/video_coding/codec_database.h b/webrtc/modules/video_coding/codec_database.h
index 4feaffe6f3f569e6caf4121d76385f3712c7f3ab..49f417953ae9c1c26c75178657c96887141a2a23 100644
--- a/webrtc/modules/video_coding/codec_database.h
+++ b/webrtc/modules/video_coding/codec_database.h
@@ -98,7 +98,7 @@ class VCMCodecDataBase {
   // |internal_render_timing| is set to true if the |external_decoder| has
   // built in rendering which is able to obey the render timestamps of the
   // encoded frames.
-  bool RegisterExternalDecoder(VideoDecoder* external_decoder,
+  void RegisterExternalDecoder(VideoDecoder* external_decoder,
                                uint8_t payload_type,
                                bool internal_render_timing);