message: fix dns impl comments
  Description: Fixes comments in dns comments in that refers to old code
  Risk Level: N/A
  Testing: N/A
  Docs Changes: N/A
  Release Notes: N/A
diff: @@ -180,7 +180,7 @@ void DnsResolverImpl::PendingResolution::onAresGetAddrInfoCallback(int status, i
  if (!completed_ && fallback_if_failed_) {
  fallback_if_failed_ = false;
  getAddrInfo(AF_INET);
  - // Note: Nothing can follow this call to getHostByName due to deletion of this
  + // Note: Nothing can follow this call to getAddrInfo due to deletion of this
  // object upon synchronous resolution.
  return;
  }
  @@ -231,7 +231,7 @@ void DnsResolverImpl::onAresSocketStateChange(os_fd_t fd, int read, int write) {
  ActiveDnsQuery* DnsResolverImpl::resolve(const std::string& dns_name,
  DnsLookupFamily dns_lookup_family, ResolveCb callback) {
  // TODO(hennna): Add DNS caching which will allow testing the edge case of a
  - // failed initial call to getHostByName followed by a synchronous IPv4
  + // failed initial call to getAddrInfo followed by a synchronous IPv4
  // resolution.
  // @see DnsResolverImpl::PendingResolution::onAresGetAddrInfoCallback for why this is done.
  