[gnome-shell] background: Disconnect from 'prepare-for-sleep' signal

[Rui Matos <rtcm src gnome org>]

commit b1dcea7cf1923bff49584751118fc8cf33f659a2
Author: Rui Matos <tiagomatos gmail com>
Date:   Mon Jan 30 13:29:13 2017 +0100

    background: Disconnect from 'prepare-for-sleep' signal
    
    This signal connection was keeping Background instances from being
    garbage collected.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=777934

 js/ui/background.js |    7 ++++++-
 1 files changed, 6 insertions(+), 1 deletions(-)
---
diff --git a/js/ui/background.js b/js/ui/background.js
index 9b36029..fc27898 100644
--- a/js/ui/background.js
+++ b/js/ui/background.js
@@ -254,7 +254,8 @@ const Background = new Lang.Class({
                     this._loadAnimation(this._animation.file);
             }));
 
-        LoginManager.getLoginManager().connect('prepare-for-sleep',
+        let loginManager = LoginManager.getLoginManager();
+        this._prepareForSleepId = loginManager.connect('prepare-for-sleep',
             (lm, aboutToSuspend) => {
                 if (aboutToSuspend)
                     return;
@@ -283,6 +284,10 @@ const Background = new Lang.Class({
             this._clock.disconnect(this._timezoneChangedId);
         this._timezoneChangedId = 0;
 
+        if (this._prepareForSleepId != 0)
+            LoginManager.getLoginManager().disconnect(this._prepareForSleepId);
+        this._prepareForSleepId = 0;
+
         if (this._settingsChangedSignalId != 0)
             this._settings.disconnect(this._settingsChangedSignalId);
         this._settingsChangedSignalId = 0;