Renders GRR home page by rendering base.html Jinja template.

def _HandleHomepage(self, request):
    """Renders GRR home page by rendering base.html Jinja template."""

    _ = request

    env = jinja2.Environment(
        loader=jinja2.FileSystemLoader(config.CONFIG["AdminUI.template_root"]),
        autoescape=True)

    create_time = psutil.Process(os.getpid()).create_time()
    context = {
        "heading":
            config.CONFIG["AdminUI.heading"],
        "report_url":
            config.CONFIG["AdminUI.report_url"],
        "help_url":
            config.CONFIG["AdminUI.help_url"],
        "timestamp":
            utils.SmartStr(create_time),
        "use_precompiled_js":
            config.CONFIG["AdminUI.use_precompiled_js"],
        # Used in conjunction with FirebaseWebAuthManager.
        "firebase_api_key":
            config.CONFIG["AdminUI.firebase_api_key"],
        "firebase_auth_domain":
            config.CONFIG["AdminUI.firebase_auth_domain"],
        "firebase_auth_provider":
            config.CONFIG["AdminUI.firebase_auth_provider"],
        "grr_version":
            config.CONFIG["Source.version_string"]
    }
    template = env.get_template("base.html")
    response = werkzeug_wrappers.Response(
        template.render(context), mimetype="text/html")

    # For a redirect-based Firebase authentication scheme we won't have any
    # user information at this point - therefore checking if the user is
    # present.
    try:
      StoreCSRFCookie(request.user, response)
    except RequestHasNoUser:
      pass

    return response