Issue 3796 - Added preference to remove developer tools panel

background.js

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-2016 Eyeo GmbH
  *
  * Adblock Plus is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 3 as
  * published by the Free Software Foundation.
  *
  * Adblock Plus is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 245 matching lines @@
         page: sender.page,
         frame: sender.frame
       }));
       break;
     case "trace-elemhide":
       devtools.logHiddenElements(
         sender.page, msg.selectors,
         extractHostFromFrame(sender.frame)
       );
       break;
+    case "has-devtools-panel":
+      sendResponse(Prefs.show_devtools_panel);
+      break;
     case "forward":
       var targetPage;
       if (msg.targetPageId)
         targetPage = ext.getPage(msg.targetPageId);
       else
         targetPage = sender.page;
 
       if (targetPage)
       {
         msg.payload.sender = sender.page.id;
         if (msg.expectsResponse)
         {
           targetPage.sendMessage(msg.payload, sendResponse);
           return true;
         }
 
         targetPage.sendMessage(msg.payload);
       }
       break;
   }
 });
 
 // update icon when page changes location
 ext.pages.onLoading.addListener(function(page)
 {
   page.sendMessage({type: "blockelement-finished"});
   refreshIconAndContextMenu(page);
   showNextNotificationForUrl(page.url);
 });