Refactor audio and video decoder status into common file.

media/base/decode_status.cc

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "media/base/decode_status.h"
+
+#include <ostream>
+
+namespace media {
+
+std::ostream& operator<<(std::ostream& os, const DecodeStatus& status) {
+  switch (status) {
+    case DecodeStatus::OK:
+      os << "DecodeStatus::OK";
+      break;
+    case DecodeStatus::ABORTED:
+      os << "DecodeStatus::ABORTED";
+      break;
+    case DecodeStatus::DECODE_ERROR:
+      os << "DecodeStatus::DECODE_ERROR";
+      break;
+  }
+  return os;
+}
+
+}  // namespace media