chromeos: Make system tray audio item observe CrasAudioHandler directly

chrome/browser/ui/ash/system_tray_delegate_chromeos.h

Index: chrome/browser/ui/ash/system_tray_delegate_chromeos.h
diff --git a/chrome/browser/ui/ash/system_tray_delegate_chromeos.h b/chrome/browser/ui/ash/system_tray_delegate_chromeos.h
index e76d94e195c3e84dc9da47a266994db8f45e612d..90f776c773746f7dc8e25d61f2cd929347b64e8b 100644
--- a/chrome/browser/ui/ash/system_tray_delegate_chromeos.h
+++ b/chrome/browser/ui/ash/system_tray_delegate_chromeos.h
@@ -27,7 +27,6 @@
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/supervised_user/supervised_user_service_observer.h"
 #include "chrome/browser/ui/browser_list_observer.h"
-#include "chromeos/audio/cras_audio_handler.h"
 #include "chromeos/dbus/session_manager_client.h"
 #include "components/policy/core/common/cloud/cloud_policy_store.h"
 #include "components/prefs/pref_change_registrar.h"
@@ -59,7 +58,6 @@ class SystemTrayDelegateChromeOS
       public SessionManagerClient::Observer,
       public content::NotificationObserver,
       public input_method::InputMethodManager::Observer,
-      public chromeos::CrasAudioHandler::AudioObserver,
       public device::BluetoothAdapter::Observer,
       public policy::CloudPolicyStore::Observer,
       public ash::SessionStateObserver,
@@ -184,15 +182,6 @@ class SystemTrayDelegateChromeOS
   void InputMethodMenuItemChanged(
       ui::ime::InputMethodMenuManager* manager) override;
 
-  // Overridden from CrasAudioHandler::AudioObserver.
-  void OnOutputNodeVolumeChanged(uint64_t node_id, int volume) override;
-  void OnOutputMuteChanged(bool mute_on, bool system_adjust) override;
-  void OnInputNodeGainChanged(uint64_t node_id, int gain) override;
-  void OnInputMuteChanged(bool mute_on) override;
-  void OnAudioNodesChanged() override;
-  void OnActiveOutputNodeChanged() override;
-  void OnActiveInputNodeChanged() override;
-
   // Overridden from BluetoothAdapter::Observer.
   void AdapterPresentChanged(device::BluetoothAdapter* adapter,
                              bool present) override;