Refactor audio and video decoder status into common file.

media/mojo/services/mojo_video_decoder.cc

Index: media/mojo/services/mojo_video_decoder.cc
diff --git a/media/mojo/services/mojo_video_decoder.cc b/media/mojo/services/mojo_video_decoder.cc
index 6f12cfe7e26c847c568f3f60d899b8cbc7c5eb6a..30b61f1f8fe6cb65c2de42c50d044f00747e353d 100644
--- a/media/mojo/services/mojo_video_decoder.cc
+++ b/media/mojo/services/mojo_video_decoder.cc
@@ -44,7 +44,8 @@ void MojoVideoDecoder::Decode(const scoped_refptr<DecoderBuffer>& buffer,
   NOTIMPLEMENTED();
 
   // Actually we can't decode anything.
-  task_runner_->PostTask(FROM_HERE, base::Bind(decode_cb, kDecodeError));
+  task_runner_->PostTask(FROM_HERE,
+                         base::Bind(decode_cb, DecoderStatus::DECODE_ERROR));
 }
 
 void MojoVideoDecoder::Reset(const base::Closure& closure) {