chromeos: Combine TrayAudio and TrayAudioChromeOs classes

ash/common/system/chromeos/audio/audio_observer.h

Index: ash/common/system/chromeos/audio/audio_observer.h
diff --git a/ash/common/system/audio/audio_observer.h b/ash/common/system/chromeos/audio/audio_observer.h
similarity index 86%
rename from ash/common/system/audio/audio_observer.h
rename to ash/common/system/chromeos/audio/audio_observer.h
index f3d485cd01ad9633e129437836489cb834f1b48c..ed937ad1b85112054bd1c856046d82c63314bc1c 100644
--- a/ash/common/system/audio/audio_observer.h
+++ b/ash/common/system/chromeos/audio/audio_observer.h
@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#ifndef ASH_COMMON_SYSTEM_AUDIO_AUDIO_OBSERVER_H_
-#define ASH_COMMON_SYSTEM_AUDIO_AUDIO_OBSERVER_H_
+#ifndef ASH_COMMON_SYSTEM_CHROMEOS_AUDIO_AUDIO_OBSERVER_H_
+#define ASH_COMMON_SYSTEM_CHROMEOS_AUDIO_AUDIO_OBSERVER_H_
 
 #include <stdint.h>
 
@@ -38,4 +38,4 @@ class AudioObserver {
 
 }  // namespace ash
 
-#endif  // ASH_COMMON_SYSTEM_AUDIO_AUDIO_OBSERVER_H_
+#endif  // ASH_COMMON_SYSTEM_CHROMEOS_AUDIO_AUDIO_OBSERVER_H_