Add a key purpose parameter to Certificate PathBuilder.

components/cast_certificate/cast_cert_validator.cc

Index: components/cast_certificate/cast_cert_validator.cc
diff --git a/components/cast_certificate/cast_cert_validator.cc b/components/cast_certificate/cast_cert_validator.cc
index ccddd3757590f8add4ee4f4fa0ff1285ae85f9fa..18609aff085b93e4bebb7f4d4bc1c237d07ba395 100644
--- a/components/cast_certificate/cast_cert_validator.cc
+++ b/components/cast_certificate/cast_cert_validator.cc
@@ -160,19 +160,9 @@ bool GetCommonNameFromSubject(const net::der::Input& subject_tlv,
   return false;
 }
 
-// Returns true if the extended key usage list |ekus| contains client auth.
-bool HasClientAuth(const std::vector<net::der::Input>& ekus) {
-  for (const auto& oid : ekus) {
-    if (oid == net::ClientAuth())
-      return true;
-  }
-  return false;
-}
-
 // Checks properties on the target certificate.
 //
 //   * The Key Usage must include Digital Signature
-//   * The Extended Key Usage must include TLS Client Auth
 //   * May have the policy 1.3.6.1.4.1.11129.2.5.2 to indicate it
 //     is an audio-only device.
 WARN_UNUSED_RESULT bool CheckTargetCertificate(
@@ -187,11 +177,6 @@ WARN_UNUSED_RESULT bool CheckTargetCertificate(
   if (!cert->key_usage().AssertsBit(net::KEY_USAGE_BIT_DIGITAL_SIGNATURE))
     return false;
 
-  // Ensure Extended Key Usage contains client auth.
-  if (!cert->has_extended_key_usage() ||
-      !HasClientAuth(cert->extended_key_usage()))
-    return false;
-
   // Check for an optional audio-only policy extension.
   *policy = CastDeviceCertPolicy::NONE;
   if (cert->has_policy_oids()) {
@@ -283,7 +268,7 @@ bool VerifyDeviceCertUsingCustomTrustStore(
   net::CertPathBuilder::Result result;
   net::CertPathBuilder path_builder(target_cert.get(), trust_store,
                                     signature_policy.get(), verification_time,
-                                    &result);
+                                    net::KeyPurpose::CLIENT_AUTH, &result);
   path_builder.AddCertIssuerSource(&intermediate_cert_issuer_source);
   path_builder.Run();
   if (!result.HasValidPath()) {