Improve determination of managed state in DeviceSettingsProvider

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 272 matching lines @@
   // See PolicyFetchRequest.policy_type.
   optional string policy_type = 1;
 
   // [timestamp] is milliseconds since Epoch in UTC timezone (Java time). It is
   // included here so that the time at which the server issued this response
   // cannot be faked (as protection against replay attacks). It is the timestamp
   // generated by DMServer, NOT the time admin last updated the policy or
   // anything like that.
   optional int64 timestamp = 2;
 
-  // The DM token that was used by the client in the HTTP POST header
-  // for authenticating the request. It is included here again so that
-  // the client can verify that the response is meant for them (and not
-  // issued by a replay or man-in-the-middle attack).
+  // The DM token that was used by the client in the HTTP POST header for
+  // authenticating the request. It is included here again so that the client
+  // can verify that the response is meant for them (and not issued by a replay
+  // or man-in-the-middle attack).
+  // Note that the existence or non-existence of the DM token is not the correct
+  // way to determine whether the device is managed. Cf. |management_mode| below
+  // for details.
   optional string request_token = 3;
 
   // The serialized value of the actual policy protobuf.  This can be
   // deserialized to an instance of, for example, ChromeSettingsProto,
   // ChromeDeviceSettingsProto, or ExternalPolicyData.
   optional bytes policy_value = 4;
 
   // The device display name assigned by the server.  It is only
   // filled if the display name is available.
   //
@@ skipping 54 matching lines @@
   optional string policy_token = 15;
 
   // Indicates the management mode of the device. Note that old policies do not
   // have this field. If this field is not set but request_token is set, assume
   // the management mode is ENTERPRISE_MANAGED. If both this field and
   // request_token are not set, assume the management mode is LOCAL_OWNER.
   enum ManagementMode {
     // The device is owned locally. The policies are set by the local owner of
     // the device.
     LOCAL_OWNER = 0;
-    // The device is enterprise-managed. The policies come from the enterprise
-    // server. See the comment above for backward compatibility.
+    // The device is enterprise-managed (either via DM server or through Active
+    // Directory). See the comment above for backward compatibility.
     ENTERPRISE_MANAGED = 1;
     // Obsolete. Don't use.
     OBSOLETE_CONSUMER_MANAGED = 2;
   }
   optional ManagementMode management_mode = 16;
 
   // Indicates the state that the device should be in.
   optional DeviceState device_state = 17;
 
   // The object source which hosts command queue objects within the
@@ skipping 1036 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;
 }