Convert some audio code to OnceCallback.

media/audio/audio_system.h

Index: media/audio/audio_system.h
diff --git a/media/audio/audio_system.h b/media/audio/audio_system.h
index 932151ed3b9fadb7fa9aff3aefc985654e6ae345..b5498ad012ff9c81009413e23ac9a28b00d55d48 100644
--- a/media/audio/audio_system.h
+++ b/media/audio/audio_system.h
@@ -5,6 +5,8 @@
 #ifndef MEDIA_AUDIO_AUDIO_SYSTEM_H_
 #define MEDIA_AUDIO_AUDIO_SYSTEM_H_
 
+#include <string>
+
 #include "base/callback.h"
 #include "media/audio/audio_device_description.h"
 #include "media/base/audio_parameters.h"
@@ -25,12 +27,13 @@ class MEDIA_EXPORT AudioSystem {
   // Replies are asynchronously sent from audio system thread to the thread the
   // call is issued on. Attention! Audio system thread may outlive the client
   // objects; bind callbacks with care.
-  using OnAudioParamsCallback = base::Callback<void(const AudioParameters&)>;
-  using OnBoolCallback = base::Callback<void(bool)>;
+  using OnAudioParamsCallback =
+      base::OnceCallback<void(const AudioParameters&)>;
+  using OnBoolCallback = base::OnceCallback<void(bool)>;
   using OnDeviceDescriptionsCallback =
-      base::Callback<void(AudioDeviceDescriptions)>;
-  using OnDeviceIdCallback = base::Callback<void(const std::string&)>;
-  using OnInputDeviceInfoCallback = base::Callback<
+      base::OnceCallback<void(AudioDeviceDescriptions)>;
+  using OnDeviceIdCallback = base::OnceCallback<void(const std::string&)>;
+  using OnInputDeviceInfoCallback = base::OnceCallback<
       void(const AudioParameters&, const AudioParameters&, const std::string&)>;
 
   // Must not be called on audio system thread if it differs from the one