Update internal SW codecs to return unique_ptrs

TBR=stefan@webrtc.org

Bug: webrtc:7925
Change-Id: I84239b071a2608d928f09b06809090eec5eafb14
Reviewed-on: https://webrtc-review.googlesource.com/21165
Commit-Queue: Magnus Jedvert <magjed@webrtc.org>
Reviewed-by: Erik Språng <sprang@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#20650}
diff --git a/modules/video_coding/generic_decoder.cc b/modules/video_coding/generic_decoder.cc
index cfe5acf..f3af20c 100644
--- a/modules/video_coding/generic_decoder.cc
+++ b/modules/video_coding/generic_decoder.cc
@@ -182,6 +182,9 @@
   return VCM_OK;
 }
 
+VCMGenericDecoder::VCMGenericDecoder(std::unique_ptr<VideoDecoder> decoder)
+    : VCMGenericDecoder(decoder.release(), false /* isExternal */) {}
+
 VCMGenericDecoder::VCMGenericDecoder(VideoDecoder* decoder, bool isExternal)
     : _callback(NULL),
       _frameInfos(),