Remove the "not_after" validation of policy timestamps

components/policy/core/common/cloud/cloud_policy_validator.h

Index: components/policy/core/common/cloud/cloud_policy_validator.h
diff --git a/components/policy/core/common/cloud/cloud_policy_validator.h b/components/policy/core/common/cloud/cloud_policy_validator.h
index b56af8959d3b82b3d0eac20894493dc92fd7f267..683155b311adae21836fce08a2c4ec078cf1c32a 100644
--- a/components/policy/core/common/cloud/cloud_policy_validator.h
+++ b/components/policy/core/common/cloud/cloud_policy_validator.h
@@ -69,7 +69,7 @@ class POLICY_EXPORT CloudPolicyValidatorBase {
     VALIDATION_WRONG_POLICY_TYPE,
     // Unexpected settings entity id.
     VALIDATION_WRONG_SETTINGS_ENTITY_ID,
-    // Time stamp outside expected range.
+    // Timestamp is missing or is older than expected.
     VALIDATION_BAD_TIMESTAMP,
     // DM token is empty or doesn't match.
     VALIDATION_BAD_DM_TOKEN,
@@ -109,14 +109,8 @@ class POLICY_EXPORT CloudPolicyValidatorBase {
 
   enum ValidateTimestampOption {
     // The policy must have a timestamp field and the timestamp is checked
-    // against both start and end times.
-    TIMESTAMP_FULLY_VALIDATED,
-
-    // The timestamp is only checked against the |not_before| value. (This is
-    // appropriate for platforms with unreliable system times where we want to
-    // ensure that fresh policy is newer than existing policy, but we can't do
-    // any other validation).
-    TIMESTAMP_NOT_BEFORE,
+    // against the |not_before| value.
+    TIMESTAMP_VALIDATED,
 
     // The timestamp is not validated.
     TIMESTAMP_NOT_VALIDATED,
@@ -138,10 +132,9 @@ class POLICY_EXPORT CloudPolicyValidatorBase {
   }
 
   // Instruct the validator to check that the policy timestamp is not before
-  // |not_before| and not after |not_after| + grace interval. Depending on
-  // |timestamp_option|, some or all of the checks may be waived.
+  // |not_before| if |timestamp_option| is TIMESTAMP_VALIDATED, or to not check
+  // the policy timestamp if |timestamp_option| is TIMESTAMP_NOT_VALIDATED.
   void ValidateTimestamp(base::Time not_before,
-                         base::Time not_after,
                          ValidateTimestampOption timestamp_option);
 
   // Instruct the validator to check that the username in the policy blob
@@ -317,7 +310,6 @@ class POLICY_EXPORT CloudPolicyValidatorBase {
 
   int validation_flags_;
   int64_t timestamp_not_before_;
-  int64_t timestamp_not_after_;
   ValidateTimestampOption timestamp_option_;
   ValidateDMTokenOption dm_token_option_;
   ValidateDeviceIdOption device_id_option_;