Initial version of ibus portal

Initial version of ibus portal

This adds a dbus service called org.freedesktop.portal.IBus on the
session bus. It is a very limited service that only implements
CreateInputContext and the InputContext interface (and Service.Destroy
for lifetime access).

It uses gdbus code generation for demarshalling the method calls which
means it will verify that all arguments have the right type.

Additionally all method calls to the input context object have to be
from the client that created it, so each client is isolated.

BUG=https://github.com/flatpak/flatpak/issues/675
R=Shawn.P.Huang@gmail.com

Committed: 203a3df5a239d644cf42b7bac03a268eb5babfc7

[fujiwara, 2017-08-28 12:45:36]

This patch is the first of two which works in Flatpak sandboxes, makes ibus
clients isolated and more secure.

Alexander Larsson provided the patches:
https://github.com/alexlarsson/ibus/tree/ibus-portal-2

[Peng, 2017-08-29 15:12:52]

On 2017/08/28 12:45:36, fujiwara wrote:
> This patch is the first of two which works in Flatpak sandboxes, makes ibus
> clients isolated and more secure.
> 
> Alexander Larsson provided the patches:
> https://github.com/alexlarsson/ibus/tree/ibus-portal-2

lgtm

[fujiwara, 2017-08-30 02:38:32]

Committed patchset #1 (id:1) manually as
203a3df5a239d644cf42b7bac03a268eb5babfc7 (presubmit successful).