Move media/audio files into media namespace

media/audio/audio_manager.cc

Index: media/audio/audio_manager.cc
diff --git a/media/audio/audio_manager.cc b/media/audio/audio_manager.cc
index d1187892116976e6e12e095165ea31b99f67431b..028b409149187c78bf9536df07cf16570b59106a 100644
--- a/media/audio/audio_manager.cc
+++ b/media/audio/audio_manager.cc
@@ -8,6 +8,8 @@
 #include "base/logging.h"
 #include "base/message_loop.h"
 
+namespace media {
+
 // Forward declaration of the platform specific AudioManager factory function.
 AudioManager* CreateAudioManager();
 
@@ -23,3 +25,5 @@ AudioManager* AudioManager::Create() {
   ret->Init();
   return ret;
 }
+
+}  // namespace media