Refactored DeviceStatusCollector to enable truely asynchronous status queries

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 715 matching lines @@
   repeated TimePeriod active_time = 4 [deprecated = true];
 
   // The browser version string as shown in the About dialog.
   // e.g. 17.0.963.18.
   optional string browser_version = 5;
 
   // A list of periods when the device was active, aggregated by day.
   repeated ActiveTimePeriod active_period = 6;
 
   // The device location.
-  optional DeviceLocation device_location = 7;
+  optional DeviceLocation deprecated_device_location = 7 [deprecated = true];
 
   // List of network interfaces.
   repeated NetworkInterface network_interface = 8;
 
   // List of recent device users, in descending order by last login time.
   repeated DeviceUser user = 9;
 
   // Disk space + other info about mounted/connected volumes.
   repeated VolumeInfo volume_info = 10;
 
@@ skipping 558 matching lines @@
   // Response to update device attribute.
   optional DeviceAttributeUpdateResponse device_attribute_update_response = 16;
 
   // Response to GCM id update request.
   optional GcmIdUpdateResponse gcm_id_update_response = 17;
 
   // Response to check Android management request.
   optional CheckAndroidManagementResponse
       check_android_management_response = 18;
 }