Kivy: Problemas con garden.cefpython

[g5server]

Estoy comenzando a probar kivy: Un framework en Python para crear app de Android.

Quiero abrir un frame para carga una URL, para eso:
He instalado garden.cefpython: https://github.com/kivy-garden/garden.cefpython

Pruebo el ejemplo en Ubuntu 14.04, pero me marca error:

cefpython: ------------------------------------------------------------
cefpython: Initialize() called
cefpython: CefExecuteProcess(): exitCode = -1
cefpython: CefInitialize()

[0616/143810:ERROR_REPORT:main_delegate.cc(448)] Check failed: false. Could not load cef.pak

[0616/143810:ERROR:zygote_host_impl_linux.cc(146)] Running without the SUID sandbox! See https://code.google.com/p/chromium/wiki/LinuxSUIDSandboxDevelopment for more information on developing with the sandbox on.
LaunchProcess: failed to execvp:
/media/jose/intercambio/Trabajos/cefpython/libs/linux64.py2/subprocess
[0616/143810:INFO:gpu_info_collector_linux.cc(78)] NVCtrl extension does not exist.
[0616/143810:ERROR:content_client.cc(91)] No data resource available for id 25003
[0616/143810:ERROR:content_client.cc(91)] No data resource available for id 25007
[0616/143810:ERROR:content_client.cc(91)] No data resource available for id 25004
cefpython: CreateBrowserSync() called
cefpython: navigateUrl: http://www.g5server.com
cefpython: CefBrowser::CreateBrowserSync()
cefpython: GetPyBrowser(): creating new PyBrowser, browserId=1
[0616/143810:ERROR_REPORT:render_widget_host_view_osr.cc(272)] Check failed: false.
cefpython: CefBrowser::CreateBrowserSync() succeeded
cefpython: SendProcessMessage(): message=DoJavascriptBindings, arguments size=1
request_keyboard()
[0616/143810:ERROR:child_process_launcher.cc(326)] Failed to launch child process
OnLoadingStateChange(): isLoading = False

¿Alguna ayuda? Gracias: José María