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

media/audio/alsa/alsa_output.h

Index: media/audio/alsa/alsa_output.h
diff --git a/media/audio/alsa/alsa_output.h b/media/audio/alsa/alsa_output.h
index e31776bf9c4264ee1592e0b1644e3fc643a478e2..f6f046a9ec95a35be1a15fdd3ea490148257c595 100644
--- a/media/audio/alsa/alsa_output.h
+++ b/media/audio/alsa/alsa_output.h
@@ -32,8 +32,8 @@
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
+#include "base/sequence_checker.h"
 #include "base/single_thread_task_runner.h"
-#include "base/threading/non_thread_safe.h"
 #include "base/time/tick_clock.h"
 #include "base/time/time.h"
 #include "media/audio/audio_io.h"
@@ -46,8 +46,7 @@ class AudioManagerBase;
 class ChannelMixer;
 class SeekableBuffer;
 
-class MEDIA_EXPORT AlsaPcmOutputStream : public AudioOutputStream,
-                                         public base::NonThreadSafe {
+class MEDIA_EXPORT AlsaPcmOutputStream : public AudioOutputStream {
  public:
   // String for the generic "default" ALSA device that has the highest
   // compatibility and chance of working.
@@ -214,6 +213,8 @@ class MEDIA_EXPORT AlsaPcmOutputStream : public AudioOutputStream,
 
   std::unique_ptr<base::TickClock> tick_clock_;
 
+  SEQUENCE_CHECKER(sequence_checker_);
+
   // Allows us to run tasks on the AlsaPcmOutputStream instance which are
   // bound by its lifetime.
   // NOTE: Weak pointers must be invalidated before all other member variables.