media: Use native DecodeStatus in media mojo interfaces

media/base/decode_status.h

Index: media/base/decode_status.h
diff --git a/media/base/decode_status.h b/media/base/decode_status.h
index 790eb5fff8c102223dcb94d521c19bc892c94977..665a9bd5dc784e46e90514f86f3639752e9f3753 100644
--- a/media/base/decode_status.h
+++ b/media/base/decode_status.h
@@ -16,6 +16,7 @@ enum class DecodeStatus {
   ABORTED,       // Read aborted due to Reset() during pending read.
   DECODE_ERROR,  // Decoder returned decode error. Note: Prefixed by DECODE_
                  // since ERROR is a reserved name (special macro) on Windows.
+  DECODE_STATUS_MAX = DECODE_ERROR
 };
 
 // Helper function so that DecodeStatus can be printed easily.