Fixes #3195 - Inconsistent granular agent permissions for chat.

db/migrate/20200923092140_issue3195_inconsistent_granular_agent_permissions_chat.rb

@@ -0,0 +1,16 @@
+class Issue3195InconsistentGranularAgentPermissionsChat < ActiveRecord::Migration[5.2]
+  def change
+    # return if it's a new setup
+    return if !Setting.exists?(name: 'system_init_done')
+
+    Permission.create_or_update(
+      name:        'chat',
+      note:        'Access to %s',
+      preferences: {
+        translations: ['Chat'],
+        disabled:     true,
+      },
+    )
+
+  end
+end

db/seeds/permissions.rb

@@ -348,7 +348,8 @@ Permission.create_if_not_exists(
   name:        'chat',
   note:        'Access to %s',
   preferences: {
-    translations: ['Chat']
+    translations: ['Chat'],
+    disabled:     true,
   },
 )
 Permission.create_if_not_exists(