Add immutable settings checks when handling policy.

chrome/browser/policy/proto/device_management_backend.proto

 // Copyright (c) 2011 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 88 matching lines @@
 
   // This is the last policy timestamp that client received from server.
   optional int64 timestamp = 2;
 
   // Tell server what kind of security signature is required.
   enum SignatureType {
     NONE = 0;
     SHA1_RSA = 1;
   }
   optional SignatureType signature_type = 3 [default = NONE];
-  
+
   // The version number of the public key that is currently stored
   // on the client. This should be the last number the server had
   // supplied as new_public_key_version in PolicyData.
   // This field is unspecified if the client does not yet have a
   // public key.
   optional int32 public_key_version = 4;
 }
 
 // This message is included in serialized form in PolicyFetchResponse
 // below.  It may also be signed, with the signature being created for
@@ skipping 21 matching lines @@
   optional bytes policy_value = 4;
 
   // The device display name assigned by the server.  It is only
   // filled if the display name is available.
   //
   // The display name of the machine as generated by the server or set
   // by the Administrator in the CPanel GUI. This is the same thing as
   // |machine_name| in DeviceRegisterResponse but it might have
   // changed since then.
   optional string machine_name = 5;
-  
+
   // Version number of the server's current public key. (The key that
   // was used to sign this response. Numbering should start at 1 and be
   // increased by 1 at each key rotation.)
   optional int32 public_key_version = 6;
-  
+
   // The user this policy is intended for. In case of device policy, the name
   // of the owner (who registered the device).
   optional string username = 7;
-  
+
   // In this field the DMServer should echo back the "deviceid" HTTP parameter
   // from the request.
   optional string device_id = 8;
 }
 
 message PolicyFetchResponse {
   // Since a single policy request may ask for multiple policies, we
   // provide separate error code for each individual policy fetch.
 
   // We will use standard HTTP Status Code as error code.
@@ skipping 96 matching lines @@
   optional string error_message = 2;
 
   // Register response
   optional DeviceRegisterResponse register_response = 3;
 
   // Unregister response
   optional DeviceUnregisterResponse unregister_response = 4;
 
   // Policy response.
   optional DevicePolicyResponse policy_response = 5;
-}
+}