Remove the "not_after" validation of policy timestamps

chrome/browser/chromeos/policy/enrollment_handler_chromeos.cc

 // Copyright (c) 2012 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.
 
 #include "chrome/browser/chromeos/policy/enrollment_handler_chromeos.h"
 
 #include <utility>
 
 #include "base/bind.h"
 #include "base/command_line.h"
@@ skipping 181 matching lines @@
         DM_STATUS_RESPONSE_DECODING_ERROR));
     return;
   }
 
   std::unique_ptr<DeviceCloudPolicyValidator> validator(
       DeviceCloudPolicyValidator::Create(
           std::unique_ptr<em::PolicyFetchResponse>(
               new em::PolicyFetchResponse(*policy)),
           background_task_runner_));
 
-  validator->ValidateTimestamp(
-      base::Time(), base::Time::NowFromSystemTime(),
-      CloudPolicyValidatorBase::TIMESTAMP_FULLY_VALIDATED);
+  validator->ValidateTimestamp(base::Time(),
+                               CloudPolicyValidatorBase::TIMESTAMP_VALIDATED);

[Thiemo Nagel, 2017/04/19 11:43:09]

Nit: IIUC it would be clearer to set TIMESTAMP_NOT_VALIDATED.

[emaxx, 2017/04/19 20:48:45]

Current code still validates something: it checks that the timestamp is present.
So I'd better leave this in place.

But I updated that the docs for ValidateTimestamp as they were misleading by not
mentioning the check of the _presence_ of the timestamp field.

 
   // If this is re-enrollment, make sure that the new policy matches the
   // previously-enrolled domain.  (Currently only implemented for cloud
   // management.)
   std::string domain;
   if (install_attributes_->IsCloudManaged()) {
     domain = install_attributes_->GetDomain();
     validator->ValidateDomain(domain);
   }
   validator->ValidateDMToken(client->dm_token(),
@@ skipping 446 matching lines @@
     callback.Run(status);
 }
 
 void EnrollmentHandlerChromeOS::SetStep(EnrollmentStep step) {
   DCHECK_LE(enrollment_step_, step);
   VLOG(1) << "Step: " << step;
   enrollment_step_ = step;
 }
 
 }  // namespace policy