Dispatch a new event chrome.contextMenus.onClicked.

chrome/common/extensions/api/context_menus.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": "contextMenus",
     "dependencies": [ "tabs" ],
     "types": [
       {
@@ skipping 39 matching lines @@
             "type": "string",
             "optional": true,
             "description": " The URL of the frame of the element where the context menu was clicked, if it was in a frame."
           },
           "selectionText": {
             "type": "string",
             "optional": true,
             "description": "The text for the context selection, if any."
           },
           "editable": {
-            "type": "string",
+            "type": "boolean",
             "description": "A flag indicating whether the element is editable (text input, textarea, etc.)."
           }
         }
       }
     ],
     "functions": [
       {
         "name": "create",
         "type": "function",
         "description": "Creates a new context menu item. Note that if an error occurs during creation, you may not find out until the creation callback fires (the details will be in chrome.extension.lastError).",
@@ skipping 36 matching lines @@
                   "type": "string",
                   "enum": ["all", "page", "frame", "selection", "link", "editable", "image", "video", "audio"]
                 },
                 "minItems": 1,
                 "optional": true,
                 "description": "List of contexts this menu item will appear in. Defaults to ['page'] if not specified."
               },
               "onclick": {
                 "type": "function",
                 "optional": true,
-                "description": "A function that will be called back when the menu item is clicked.",
+                "description": "A function that will be called back when the menu item is clicked. Event pages cannot use this; instead, they should register a listener for chrome.contextMenus.onClicked.",
                 "parameters": [
                   {
                     "name": "info",
                     "$ref": "OnClickData",
                     "description": "Information about the item clicked and the context where the click happened."
                   },
                   {
                     "name": "tab",
                     "$ref": "tabs.Tab",
                     "description": "The details of the tab where the click took place."
@@ skipping 142 matching lines @@
         "parameters": [
           {
             "type": "function",
             "name": "callback",
             "optional": true,
             "parameters": [],
             "description": "Called when removal is complete."
           }
         ]
       }
+    ],
+    "events": [
+      {
+        "name": "onClicked",
+        "type": "function",
+        "description": "Fired when a context menu item is clicked.",
+        "parameters": [
+          {
+            "name": "info",
+            "$ref": "OnClickData",
+            "description": "Information about the item clicked and the context where the click happened."
+          },
+          {
+            "name": "tab",
+            "$ref": "tabs.Tab",
+            "description": "The details of the tab where the click took place."
+          }
+        ]
+      }
     ]
   }
 ]