[gnome-documents] preview: Use g_action_change_state

[Alessandro Bono <abono src gnome org>]

commit 94dc788a6aa683a995e1c3e19644d8fa93a8bcd4
Author: Alessandro Bono <abono gnome org>
Date:   Mon Jan 25 23:12:44 2016 +0100

    preview: Use g_action_change_state
    
    According to:
    https://developer.gnome.org/gio/stable/GSimpleAction.html#g-simple-action-set-state
    
    https://bugzilla.gnome.org/show_bug.cgi?id=765342

 src/preview.js |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/src/preview.js b/src/preview.js
index c7804bc..40aedce 100644
--- a/src/preview.js
+++ b/src/preview.js
@@ -222,7 +222,7 @@ const PreviewView = new Lang.Class({
         let bookmark = new GdPrivate.Bookmark({ page_number: page_number });
         let hasBookmark = (this._bookmarks.find_bookmark(bookmark) != null);
 
-        this._bookmarkPage.state = GLib.Variant.new('b', hasBookmark);
+        this._bookmarkPage.change_state(GLib.Variant.new('b', hasBookmark));
     },
 
     _setError: function(primary, secondary) {