[gnome-shell/wip/fix-screen-shield-motion-handler-leak] screenShield: Fix pointer motion signal handler leak

[Ray Strode <halfline src gnome org>]

commit a270014b4385020bd658cba979f04b0f34eec1f6
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.

 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 b368162ce8..52baae8ff2 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;