[gnome-shell/gnome-3-38] screenShield: Fix pointer motion signal handler leak

[Florian Müllner <fmuellner src gnome org>]

commit dddac39d1fb5d1a8b40799f684143c622b91b11f
Author: Ray Strode <rstrode redhat com>
Date:   Mon Sep 28 22:28:08 2020 -0400

    screenShield: Fix pointer motion signal handler leak
    
    The screen shield code listens for motion events on the stage
    so that it can hide the pointer until the user moves the mouse.
    
    Unfortunately, if the user never moves the mouse, the signal
    handler connection gets leaked.
    
    This commit makes sure the connection gets disconnected when the
    shield goes away.
    
    https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/1459

 js/ui/screenShield.js | 31 +++++++++++++++++++++----------
 1 file changed, 21 insertions(+), 10 deletions(-)
---
diff --git a/js/ui/screenShield.js b/js/ui/screenShield.js
index 9beece6465..fa3a7a8167 100644
--- a/js/ui/screenShield.js
+++ b/js/ui/screenShield.js
@@ -336,6 +336,25 @@ var ScreenShield = class {
         }
     }
 
+    _showPointer() {
+        this._cursorTracker.set_pointer_visible(true);
+
+        if (this._motionId) {
+            global.stage.disconnect(this._motionId);
+            this._motionId = 0;
+        }
+    }
+
+    _hidePointerUntilMotion() {
+        this._motionId = global.stage.connect('captured-event', (stage, event) => {
+            if (event.type() === Clutter.EventType.MOTION)
+                this._showPointer();
+
+            return Clutter.EVENT_PROPAGATE;
+        });
+        this._cursorTracker.set_pointer_visible(false);
+    }
+
     _hideLockScreen(animate) {
         if (this._lockScreenState == MessageTray.State.HIDDEN)
             return;
@@ -364,7 +383,7 @@ var ScreenShield = class {
             this._hideLockScreenComplete();
         }
 
-        this._cursorTracker.set_pointer_visible(true);
+        this._showPointer();
     }
 
     _ensureUnlockDialog(allowCancel) {
@@ -435,15 +454,7 @@ var ScreenShield = class {
     }
 
     _lockScreenShown(params) {
-        let motionId = global.stage.connect('captured-event', (stage, event) => {
-            if (event.type() === Clutter.EventType.MOTION) {
-                this._cursorTracker.set_pointer_visible(true);
-                global.stage.disconnect(motionId);
-            }
-
-            return Clutter.EVENT_PROPAGATE;
-        });
-        this._cursorTracker.set_pointer_visible(false);
+        this._hidePointerUntilMotion();
 
         this._lockScreenState = MessageTray.State.SHOWN;