sessionMode: Drop allowExtensions property

Now that we allow extensions at the lock screens, extensions
are allowed for every session mode gnome-shell would typically
change to at runtime.

This means there's little advantage to having an allowExtensions
property in the session mode definition.

This commit simplifies the code a bit by dropping the property.

Third party session modes can still lock down extensions through
gsettings if they need to.

Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/1967>

js/ui/extensionSystem.js

@@ -88,16 +88,6 @@ var ExtensionManager = class {
         return false;
     }
 
-    _sessionModeCanUseExtension(uuid) {
-        if (!Main.sessionMode.allowExtensions)
-            return false;
-
-        if (!this._extensionSupportsSessionMode(uuid))
-            return false;
-
-        return true;
-    }
-
     _callExtensionDisable(uuid) {
         let extension = this.lookup(uuid);
         if (!extension)
@@ -157,7 +147,7 @@ var ExtensionManager = class {
     }
 
     _callExtensionEnable(uuid) {
-        if (!this._sessionModeCanUseExtension(uuid))
+        if (!this._extensionSupportsSessionMode(uuid))
             return;
 
         let extension = this.lookup(uuid);
@@ -424,7 +414,7 @@ var ExtensionManager = class {
     }
 
     _callExtensionInit(uuid) {
-        if (!this._sessionModeCanUseExtension(uuid))
+        if (!this._extensionSupportsSessionMode(uuid))
             return false;
 
         let extension = this.lookup(uuid);
@@ -635,17 +625,9 @@ var ExtensionManager = class {
     }
 
     _sessionUpdated() {
-        // For now sessionMode.allowExtensions controls extensions from both the
-        // 'enabled-extensions' preference and the sessionMode.enabledExtensions
-        // property; it might make sense to make enabledExtensions independent
-        // from allowExtensions in the future
-        if (Main.sessionMode.allowExtensions) {
         // Take care of added or removed sessionMode extensions
         this._onEnabledExtensionsChanged();
         this._enableAllExtensions();
-        } else {
-            this._disableAllExtensions();
-        }
     }
 };
 Signals.addSignalMethods(ExtensionManager.prototype);

js/ui/sessionMode.js

@@ -20,7 +20,6 @@ const _modes = {
         showCalendarEvents: false,
         showWelcomeDialog: false,
         allowSettings: false,
-        allowExtensions: false,
         allowScreencast: false,
         enabledExtensions: [],
         hasRunDialog: false,
@@ -42,7 +41,6 @@ const _modes = {
     },
 
     'gdm': {
-        allowExtensions: true,
         hasNotifications: true,
         isGreeter: true,
         isPrimary: true,
@@ -59,7 +57,6 @@ const _modes = {
     },
 
     'unlock-dialog': {
-        allowExtensions: true,
         isLocked: true,
         unlockDialog: undefined,
         components: ['polkitAgent', 'telepathyClient'],
@@ -76,7 +73,6 @@ const _modes = {
         showCalendarEvents: true,
         showWelcomeDialog: true,
         allowSettings: true,
-        allowExtensions: true,
         allowScreencast: true,
         hasRunDialog: true,
         hasWorkspaces: true,