extensionUtils: Add DISABLING and ENABLING extension states

Extensions can export asynchronous enable() and disable()
functions. To guard against re-entrancy when enabling or
disabling an extension, this commit adds two new states:
ENABLING and DISABLING which are set immediately prior
to calling enable() and disable() respectively.

This commit updates the extensions CLI and Extensions app
with new strings for these states.

Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/2364>

js/misc/extensionUtils.js

@@ -38,6 +38,8 @@ var ExtensionState = {
     OUT_OF_DATE: 4,
     DOWNLOADING: 5,
     INITIALIZED: 6,
+    DISABLING: 7,
+    ENABLING: 8,
 
     // Used as an error state for operations on unknown extensions,
     // should never be in a real extensionMeta object.

js/ui/extensionSystem.js

@@ -100,6 +100,9 @@ var ExtensionManager = class extends Signals.EventEmitter {
         if (extension.state != ExtensionState.ENABLED)
             return;
 
+        extension.state = ExtensionState.DISABLING;
+        this.emit('extension-state-changed', extension);
+
         // "Rebase" the extension order by disabling and then enabling extensions
         // in order to help prevent conflicts.
 
@@ -164,6 +167,9 @@ var ExtensionManager = class extends Signals.EventEmitter {
         if (extension.state != ExtensionState.DISABLED)
             return;
 
+        extension.state = ExtensionState.ENABLING;
+        this.emit('extension-state-changed', extension);
+
         let stylesheetNames = [`${global.session_mode}.css`, 'stylesheet.css'];
         let theme = St.ThemeContext.get_for_stage(global.stage).get_theme();
         for (let i = 0; i < stylesheetNames.length; i++) {

js/ui/lookingGlass.js

@@ -790,16 +790,20 @@ var Extensions = GObject.registerClass({
     _stateToString(extensionState) {
         switch (extensionState) {
         case ExtensionState.ENABLED:
-            return _("Enabled");
+            return _('Enabled');
         case ExtensionState.DISABLED:
         case ExtensionState.INITIALIZED:
-            return _("Disabled");
+            return _('Disabled');
         case ExtensionState.ERROR:
-            return _("Error");
+            return _('Error');
         case ExtensionState.OUT_OF_DATE:
-            return _("Out of date");
+            return _('Out of date');
         case ExtensionState.DOWNLOADING:
-            return _("Downloading");
+            return _('Downloading');
+        case ExtensionState.DISABLING:
+            return _('Disabling');
+        case ExtensionState.ENABLING:
+            return _('Enabling');
         }
         return 'Unknown'; // Not translated, shouldn't appear
     }