Add sound volume to device attribute reporting

components/policy/proto/device_management_backend.proto

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 syntax = "proto2";
 
 option optimize_for = LITE_RUNTIME;
 
 package enterprise_management;
 
@@ skipping 749 matching lines @@
   repeated CPUTempInfo cpu_temp_info = 16;
 
   // This field is set only when an OS update is needed because of the required
   // platform version of an updated kiosk app is different from the current
   // OS version.
   optional OsUpdateStatus os_update_status = 17;
 
   // Set only when there is an auto launched with zero delay kiosk app
   // and it is currently running. Otherwise, this field is empty.
   optional AppStatus running_kiosk_app = 18;
+
+  // Sound output volume level in range [0,100].
+  optional int32 sound_volume = 19;
 }
 
 message OsUpdateStatus {
   enum UpdateStatus {
     OS_UP_TO_DATE = 0;
     OS_IMAGE_DOWNLOAD_NOT_STARTED = 1;
     OS_IMAGE_DOWNLOAD_IN_PROGRESS = 2;
     OS_UPDATE_NEED_REBOOT = 3;
   }
 
@@ skipping 694 matching lines @@
       check_android_management_response = 18;
 
   // Response to an Active Directory Play user enrollment request.
   optional ActiveDirectoryEnrollPlayUserResponse
       active_directory_enroll_play_user_response = 19;
 
   // Response to a Play activity request.
   optional ActiveDirectoryPlayActivityResponse
       active_directory_play_activity_response = 20;
 }