Otherwise it will again lead to:
  GLib-GIO-CRITICAL **:
    g_dbus_interface_skeleton_unexport_from_connection: assertion
    'interface_->priv->connections != NULL' failed

https://bugzilla.gnome.org/show_bug.cgi?id=783548

The ShellSearchProvider should be instantiated in the dbus_register
virtual method, which is expected to be called only once.

https://bugzilla.gnome.org/show_bug.cgi?id=783548

Now that the --version flag was implemented using the
handle_local_options virtual method, it is possible that the
Application may exit without ever touching D-Bus. So it is a tad
wasteful to instantiate the ShellSearchProvider when it is never going
to be used. Since we are unreffing it in dbus_register, we might as
well create it in dbus_register.

https://bugzilla.gnome.org/show_bug.cgi?id=783548

The dbus_unregister method can be invoked more than once. Trying to
unexport an already unexported GDBusInterfaceSkeleton led to:
  GLib-GIO-CRITICAL **:
    g_dbus_interface_skeleton_unexport_from_connection: assertion
    'interface_->priv->connections != NULL' failed

https://bugzilla.gnome.org/show_bug.cgi?id=783548

Now that we don't convert everything to PDFs, we might not be able to
print everything that's not a collection. eg., we can't print EPUBs,
ODFs and OOXMLs. Therefore it is not enough to only check for
collecitons.

https://bugzilla.gnome.org/show_bug.cgi?id=781533

https://bugzilla.gnome.org/show_bug.cgi?id=781533

https://bugzilla.gnome.org/show_bug.cgi?id=781533

https://bugzilla.gnome.org/show_bug.cgi?id=781531

All the remote document types have the exact same load implementation.
Instead of keeping multiple copies of that code, it's better to share
it via the base class. In theory, we can use the same code for
LocalDocument too, but we already have a trivial implementation that
avoids some needless I/O so it's better to retain it.

https://bugzilla.gnome.org/show_bug.cgi?id=781032

There is no longer a pressing need to convert documents to PDFs because
we have the option of using LibreOffice to render them. Even though
GoogleDocuments are still converted to PDF, that's entirely handled
on the server-side.

This code was also using a bunch of legacy technologies, like X and
PackageKit, without having support for more modern alternatives like
Wayland and Flatpak. So it's good to be able to finally remove it.

https://bugzilla.gnome.org/show_bug.cgi?id=781032

Fallout from a1ce7d22

https://bugzilla.gnome.org/show_bug.cgi?id=781032

As a positive side-effect this restores the caching for ODFs and
OOXMLs from ownCloud.

https://bugzilla.gnome.org/show_bug.cgi?id=781032

https://bugzilla.gnome.org/show_bug.cgi?id=781032

All GoogleDocuments are still downloaded as PDFs, but there is no
reason to do that using GdPdfLoader. It can be done in JavaScript using
the new downloadImpl virtual method.

This further simplifies GdPdfLoader and is another step forward in
unifying the loading across the various sub-classes.

https://bugzilla.gnome.org/show_bug.cgi?id=781032

This will let us use the new JavaScript-based download and caching
implementation and reduce our reliance on GdPdfLoader.

https://bugzilla.gnome.org/show_bug.cgi?id=781032

This will let us use the new JavaScript-based download and caching
implementation and reduce our reliance on GdPdfLoader.

https://bugzilla.gnome.org/show_bug.cgi?id=781032

Gio.FILE_ATTRIBUTE_TIME_MODIFIED returns a value in seconds, not
microseconds.

Fallout from 4133adf0

https://bugzilla.gnome.org/show_bug.cgi?id=774937

OneDrive documents were being converted to PDFs via GdPdfLoader, but
LOKDocView was being used instead of EvView to render them. LOKDocView
uses the document's URI property, and in this case it is not a valid
URI that it can use. As a result the preview would fail and sometimes
crash the application.

Solve all that by removing the PDF conversion, and passing the correct
URI to LOKDocView.

This effectively reverts 0bfb2378

https://bugzilla.gnome.org/show_bug.cgi?id=774937

https://bugzilla.gnome.org/show_bug.cgi?id=774937

This is meant to reduce our reliance on GdPdfLoader for loading remote
documents. We can open ODFs and OOXMLs in LOKDocView, so we don't need
to convert everything to PDFs. In the future, remote sub-classes will
provider their own implementation to download a document, and this will
help unify the loading across the various sub-classes.

https://bugzilla.gnome.org/show_bug.cgi?id=774937

We want to open ODFs and OOXMLs from OneDrive using LOKDocView, not
EvView. Therefore, the logic to convert a remote document into
something that can be loaded by the different preview widgets can no
longer be hidden inside GdPdfLoader. LOKDocView needs to know the URI
it can load without hitting the network.

For local and ownCloud this is the same as the actual URI because they
are natively handled by GIO. The property is not defined for Google
because it is still handled entirely by GdPdfLoader.

This changes the caching for SkydriveDocuments. The old scheme was:
  ~/.cache/gnome-documents/gnome-documents-<g_str_hash(id)>.pdf
The new structure is:
  ~/.cache/gnome-documents/skydrive/<SHA1(id)>.<original-extension>

The new scheme namespaces each document type and uses a hash function
that can be easily replicated by other tools for debugging. This is a
good time to change this because we are about to invalidate existing
caches by not using the ".pdf" extension for all SkydriveDocuments.

https://bugzilla.gnome.org/show_bug.cgi?id=774937

Now that we can open ODFs and OOXMLs in LOKDocView, we don't need to
convert all remote documents to PDF. For example, we can open office
documents stored from OneDrive without any format conversion. The
nfo:fileName can be used to determine the extension of the cached file.

https://bugzilla.gnome.org/show_bug.cgi?id=774937

https://bugzilla.gnome.org/show_bug.cgi?id=781455

https://bugzilla.gnome.org/show_bug.cgi?id=780780

It's more readable to unconditionally initialize everything that needs
to be cleaned up, and do the clean up as part of the 'out' stanza. This
is also how g_auto* works, so it brings us a step closer to it.

https://bugzilla.gnome.org/show_bug.cgi?id=780780

We can use GObject signals and remove this quirk.

So that it can be also used e.g. in the epub backend.

Not before; the parent implementation may call into some methods that
require a model.

So that we can extend it also to other backends, such as the epub one.

Don't mess with the toolbar sensitivity; hiding it is enough. Also,
make sure the menu is closed when we enter or leave fullscreen.