Hide the definition of MessagePumpGtk::GetDefaultXDisplay.

Change-Id: I3bcee32bcdaab3fe43dc02a66cac295bb1c6386e
Reviewed-by: Zeno Albisser <zeno.albisser@digia.com>
Add accessors for the Qt delegated renderer integration.

This is needed to fetch the MessageLoop, the MailboxManager and the
SyncPointManager of the GPU in-process host.

Change-Id: Ide000254dc8525e00388df8fd182f77405f8451c
Reviewed-by: Zeno Albisser <zeno.albisser@digia.com>
Add seams to setup GL contexts sharing with QtQuick.

This will allow us to know right before the first GL context is
instantiated by Chromium so that we can install those contexts to
be shared with QtQuick GL contexts as well.

Change-Id: Ia2de987edb5a87097c2b29bedd8a1f908141d8ee
Reviewed-by: Zeno Albisser <zeno.albisser@digia.com>