[gnome-documents] preview: ensure signals/sources are removed upon destroy

[Cosimo Cecchi <cosimoc src gnome org>]

commit 990871da0dc9a8a9e9aa53d714d39cb0b8d83141
Author: Cosimo Cecchi <cosimoc gnome org>
Date:   Sat Aug 3 18:33:35 2019 +0200

    preview: ensure signals/sources are removed upon destroy
    
    Some of the objects (e.g. the overlay) will outlive the preview, so
    we need to disconnect signals from them when the preview or one of
    its subcomponents are destroyed.
    
    Also, we were not properly cleaning up some sources upon destruction
    of the nav bar controls.

 src/preview.js | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)
---
diff --git a/src/preview.js b/src/preview.js
index 8382f50d..d7c2456b 100644
--- a/src/preview.js
+++ b/src/preview.js
@@ -590,7 +590,7 @@ var PreviewNavControls = class PreviewNavControls {
         this._prevRevealer.show_all();
         this._nextRevealer.show_all();
 
-        this._overlay.connect('motion-notify-event', this._onMotion.bind(this));
+        this._overlayMotionId = this._overlay.connect('motion-notify-event', this._onMotion.bind(this));
 
         this._tapGesture = new Gtk.GestureMultiPress({ propagation_phase: Gtk.PropagationPhase.CAPTURE,
                                                        touch_only: true,
@@ -613,6 +613,14 @@ var PreviewNavControls = class PreviewNavControls {
         return false;
     }
 
+    _removeMotionTimeout() {
+        if (this._motionId == 0)
+            return;
+
+        Mainloop.source_remove(this._motionId);
+        this._motionId = 0;
+    }
+
     _motionTimeout() {
         this._motionId = 0;
         this._visibleInternal = true;
@@ -706,6 +714,14 @@ var PreviewNavControls = class PreviewNavControls {
     }
 
     destroy() {
+        this._unqueueAutoHide();
+        this._removeMotionTimeout();
+
+        if (this._overlayMotionId != 0) {
+            this._overlay.disconnect(this._overlayMotionId);
+            this._overlayMotionId = 0;
+        }
+
         if (this._barRevealer)
             this._barRevealer.destroy();
         this._prevRevealer.destroy();