FIX: use current_user.id in onebox instead of param

app/assets/javascripts/pretty-text/oneboxer.js.es6

@@ -48,7 +48,7 @@ function loadNext(ajax) {
   // Retrieve the onebox
   return ajax("/onebox", {
     dataType: 'html',
-    data: { url, refresh, user_id: userId },
+    data: { url, refresh },
     cache: true
   }).then(html => {
     let $html = $(html);

app/controllers/onebox_controller.rb

@@ -4,7 +4,6 @@ class OneboxController < ApplicationController
   before_action :ensure_logged_in
 
   def show
-    params.require(:user_id)
 
     unless params[:refresh] == 'true'
       preview = Oneboxer.cached_preview(params[:url])
@@ -13,15 +12,15 @@ class OneboxController < ApplicationController
     end
 
     # only 1 outgoing preview per user
-    return render(body: nil, status: 429) if Oneboxer.is_previewing?(params[:user_id])
+    return render(body: nil, status: 429) if Oneboxer.is_previewing?(current_user.id)
 
-    Oneboxer.preview_onebox!(params[:user_id])
+    Oneboxer.preview_onebox!(current_user.id)
 
     preview = Oneboxer.preview(params[:url], invalidate_oneboxes: params[:refresh] == 'true')
     preview.strip! if preview.present?
 
     Scheduler::Defer.later("Onebox previewed") {
-      Oneboxer.onebox_previewed!(params[:user_id])
+      Oneboxer.onebox_previewed!(current_user.id)
     }
 
     if preview.blank?