Support shared workers as debug targets for chrome.debugger API

chrome/common/extensions/api/debugger.json

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 [
   {
     "namespace": "debugger",
     "types": [
       {
         "id": "Debuggee",
         "type": "object",
         "description": "Debuggee identifier. Either tabId or extensionId must be specified",
         "properties": {
           "tabId": { "type": "integer", "optional": true, "description": "The id of the tab which you intend to debug." },
           "extensionId": { "type": "string", "optional": true, "description": "The id of the extension which you intend to debug. Attaching to an extension background page is only possible when 'enable-silent-debugging' flag is enabled on the target browser." },
           "targetId": { "type": "string", "optional": true, "description": "The opaque id of the debug target." }
         }
       },
       {
         "id": "TargetInfo",
         "type": "object",
         "description": "Debug target information",
         "properties": {
           "type": {
             "type": "string",
             "description": "Target type.",
-            "enum" : ["page", "background_page", "other" ]
+            "enum" : ["page", "background_page", "worker", "other" ]
           },
           "id": { "type": "string", "description": "Target id." },
           "attached": { "type": "boolean", "description": "True if debugger is already attached." },
           "title": { "type": "string", "description": "Target page title." },
           "url": { "type": "string", "description": "Target URL." },
           "faviconUrl": { "type": "string", "optional": true, "description": "Target favicon URL." }
         }
       }
     ],
     "functions": [
@@ skipping 138 matching lines @@
             "type": "string",
             "name": "reason",
             "description": "Connection termination reason.",
             "enum": [ "target_closed", "canceled_by_user", "replaced_with_devtools" ]
           }
         ]
       }
     ]
   }
 ]