Merge "Better document the ignore behavior for client cert api" into nyc-dev

     * in memory (for the life of the application) if proceed() or cancel() is

     * called and does not call onReceivedClientCertRequest() again for the

     * same host and port pair. Webview does not store the response if ignore()

     * is called.

     * is called. Note that, multiple layers in chromium network stack might be

     * caching the responses, so the behavior for ignore is only a best case

     * effort.

     *

     * This method is called on the UI thread. During the callback, the

     * connection is suspended.