Sanitize headers in Proxy Authentication Required responses

BUG=431504

Review URL: https://codereview.chromium.org/769043003

Cr-Commit-Position: refs/heads/master@{#310014}
HttpStream* SpdyProxyClientSocket::CreateConnectResponseStream() {
  return new ProxyConnectRedirectHttpStream(
      redirect_has_load_timing_info_ ? &redirect_load_timing_info_ : NULL);
}

HttpStream* SpdyProxyClientSocket::CreateConnectResponseStream() {
  return new ProxyConnectRedirectHttpStream(
      redirect_has_load_timing_info_ ? &redirect_load_timing_info_ : NULL);
}
