Move list of valid origin prefixes for incoming WebSocket requests to a constant

Summary: Create a constant to hold all valid origin prefixes, for incoming WebSocket requests. This is to make it easier to add additional origins.

Reviewed By: mweststrate

Differential Revision: D26778708

fbshipit-source-id: b89bd8c8d8925b2863f12c319c6ecbeeb265fc42

desktop/app/src/fb-stubs/constants.tsx

@@ -42,4 +42,12 @@ export default Object.freeze({
   },
 
   SUPPORT_GROUPS: [],
+
+  // Only WebSocket requests from the following origin prefixes will be accepted
+  VALID_WEB_SOCKET_REQUEST_ORIGIN_PREFIXES: [
+    'chrome-extension://',
+    'localhost:',
+    'http://localhost:',
+    'app://',
+  ],
 });