From a4a6aa18d7a69c6d10a1701130a545a7bf4b1473 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Emilio=20Cobos=20=C3=81lvarez?= <emilio@crisal.io>
Date: Thu, 7 Jul 2022 21:17:36 +0000
Subject: [PATCH] Bug 1778444 - Clear UISettings on shutdown. r=kaie

This should be the right fix.

Differential Revision: https://phabricator.services.mozilla.com/D151311
---
 widget/windows/WindowsUIUtils.cpp | 20 +++++++++++++-------
 1 file changed, 13 insertions(+), 7 deletions(-)

diff --git a/widget/windows/WindowsUIUtils.cpp b/widget/windows/WindowsUIUtils.cpp
index f769e2afc6f1..9b816ec1fb70 100644
--- a/widget/windows/WindowsUIUtils.cpp
+++ b/widget/windows/WindowsUIUtils.cpp
@@ -14,6 +14,7 @@
 #include "nsIObserverService.h"
 #include "nsIAppShellService.h"
 #include "nsAppShellCID.h"
+#include "mozilla/ClearOnShutdown.h"
 #include "mozilla/ResultVariant.h"
 #include "mozilla/Services.h"
 #include "mozilla/StaticPrefs_widget.h"
@@ -339,23 +340,25 @@ static IInspectable* GetUISettings() {
 #ifndef __MINGW32__
   // We need to keep this alive for ~ever so that change callbacks work as
   // expected, sigh.
-  static ComPtr<IInspectable> sUiSettingsAsInspectable;
+  static StaticRefPtr<IInspectable> sUiSettingsAsInspectable;
+
   if (!IsWin10OrLater()) {
     // Windows.UI.ViewManagement.UISettings is Win10+ only.
     return nullptr;
   }
 
   if (!sUiSettingsAsInspectable) {
+    ComPtr<IInspectable> uiSettingsAsInspectable;
     ::RoActivateInstance(
         HStringReference(RuntimeClass_Windows_UI_ViewManagement_UISettings)
             .Get(),
-        &sUiSettingsAsInspectable);
-    if (NS_WARN_IF(!sUiSettingsAsInspectable)) {
+        &uiSettingsAsInspectable);
+    if (NS_WARN_IF(!uiSettingsAsInspectable)) {
       return nullptr;
     }
 
     ComPtr<IUISettings5> uiSettings5;
-    if (SUCCEEDED(sUiSettingsAsInspectable.As(&uiSettings5))) {
+    if (SUCCEEDED(uiSettingsAsInspectable.As(&uiSettings5))) {
       EventRegistrationToken unusedToken;
       auto callback = Callback<ITypedEventHandler<
           UISettings*, UISettingsAutoHideScrollBarsChangedEventArgs*>>(
@@ -370,7 +373,7 @@ static IInspectable* GetUISettings() {
     }
 
     ComPtr<IUISettings2> uiSettings2;
-    if (SUCCEEDED(sUiSettingsAsInspectable.As(&uiSettings2))) {
+    if (SUCCEEDED(uiSettingsAsInspectable.As(&uiSettings2))) {
       EventRegistrationToken unusedToken;
       auto callback =
           Callback<ITypedEventHandler<UISettings*, IInspectable*>>([](auto...) {
@@ -384,7 +387,7 @@ static IInspectable* GetUISettings() {
     }
 
     ComPtr<IUISettings3> uiSettings3;
-    if (SUCCEEDED(sUiSettingsAsInspectable.As(&uiSettings3))) {
+    if (SUCCEEDED(uiSettingsAsInspectable.As(&uiSettings3))) {
       EventRegistrationToken unusedToken;
       auto callback =
           Callback<ITypedEventHandler<UISettings*, IInspectable*>>([](auto...) {
@@ -396,9 +399,12 @@ static IInspectable* GetUISettings() {
       (void)NS_WARN_IF(FAILED(
           uiSettings3->add_ColorValuesChanged(callback.Get(), &unusedToken)));
     }
+
+    sUiSettingsAsInspectable = dont_AddRef(uiSettingsAsInspectable.Detach());
+    ClearOnShutdown(&sUiSettingsAsInspectable);
   }
 
-  return sUiSettingsAsInspectable.Get();
+  return sUiSettingsAsInspectable.get();
 #else
   return nullptr;
 #endif