Replace deprecated base::NonThreadSafe in media/audio in favor of SequenceChecker.

media/audio/sounds/audio_stream_handler.h

Index: media/audio/sounds/audio_stream_handler.h
diff --git a/media/audio/sounds/audio_stream_handler.h b/media/audio/sounds/audio_stream_handler.h
index 009021fd171b7c265433fd437ca86aebaae27169..0e1de61be4c8566ab6a43e1a94eda836446b8a91 100644
--- a/media/audio/sounds/audio_stream_handler.h
+++ b/media/audio/sounds/audio_stream_handler.h
@@ -11,8 +11,8 @@
 
 #include "base/compiler_specific.h"
 #include "base/macros.h"
+#include "base/sequence_checker.h"
 #include "base/strings/string_piece.h"
-#include "base/threading/non_thread_safe.h"
 #include "base/time/time.h"
 #include "media/audio/audio_io.h"
 #include "media/base/audio_parameters.h"
@@ -21,7 +21,7 @@
 namespace media {
 
 // This class sends a sound to the audio manager.
-class MEDIA_EXPORT AudioStreamHandler : public base::NonThreadSafe {
+class MEDIA_EXPORT AudioStreamHandler {
  public:
   class TestObserver {
    public:
@@ -71,6 +71,8 @@ class MEDIA_EXPORT AudioStreamHandler : public base::NonThreadSafe {
   base::TimeDelta duration_;
   std::unique_ptr<AudioStreamContainer> stream_;
 
+  SEQUENCE_CHECKER(sequence_checker_);
+
   DISALLOW_COPY_AND_ASSIGN(AudioStreamHandler);
 };