[gnome-shell] a11y: Change HC icon theme first

[Georges Basile Stavracas Neto <gbsneto src gnome org>]

commit 36b8dcbe076a02d5687238bb5ac999dd43277a65
Author: Florian Müllner <fmuellner gnome org>
Date:   Sat Dec 14 19:15:53 2019 +0100

    a11y: Change HC icon theme first
    
    There are two ways for applications to provide a high contrast icon:
    
     1. install an icon into the HighContrast theme
     2. install a symbolic icon into the default hicolor theme
    
    The latter is preferred nowadays, and implemented in the high-contrast
    CSS variant by enforcing the symbolic icon style.
    
    However together with the way we currently enable/disable high-contrast,
    this can lead to the following race:
     1. the GTK theme is changed from HighContrast
     2. we reload the default stylesheet
     3. the icon style changes to "regular", so we request a
        new icon from the HighContrast icon theme
     4. the icon theme is changed from HighContrast
     5. we evict existing icons from the cache
     6. we reload icons for the new icon theme; however as we
        find a pending request (from 3), we re-use it
     7. the request from 3 finishes, and we end up with a
        wrong icon in the cache
    
    The simplest fix is to change the icon theme before the GTK theme: Unlike the
    theme name, the icon style is encoded in the cache key, so we won't re-use
    an old (and incorrect) request in that case.
    
    https://gitlab.gnome.org/GNOME/gnome-shell/issues/2414

 js/ui/status/accessibility.js | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)
---
diff --git a/js/ui/status/accessibility.js b/js/ui/status/accessibility.js
index 206ed5114c..04406e2255 100644
--- a/js/ui/status/accessibility.js
+++ b/js/ui/status/accessibility.js
@@ -139,14 +139,14 @@ class ATIndicator extends PanelMenu.Button {
             interfaceSettings.is_writable(KEY_ICON_THEME),
             enabled => {
                 if (enabled) {
-                    interfaceSettings.set_string(KEY_GTK_THEME, HIGH_CONTRAST_THEME);
                     interfaceSettings.set_string(KEY_ICON_THEME, HIGH_CONTRAST_THEME);
+                    interfaceSettings.set_string(KEY_GTK_THEME, HIGH_CONTRAST_THEME);
                 } else if (!hasHC) {
-                    interfaceSettings.set_string(KEY_GTK_THEME, gtkTheme);
                     interfaceSettings.set_string(KEY_ICON_THEME, iconTheme);
+                    interfaceSettings.set_string(KEY_GTK_THEME, gtkTheme);
                 } else {
-                    interfaceSettings.reset(KEY_GTK_THEME);
                     interfaceSettings.reset(KEY_ICON_THEME);
+                    interfaceSettings.reset(KEY_GTK_THEME);
                 }
             });