Issue 21729: Add new event chrome.tabs.onStatusChange .

chrome/common/extensions/api/extension_api.json

 [
   {
     "namespace": "extension",
     "types": [
       {
         "id": "Port",
         "type": "object",
         "description": "An object which allows two way communication with other pages.",
         "properties": {
           "name": {"type": "string"},
@@ skipping 711 matching lines @@
       },
       {
         "name": "onUpdated",
         "type": "function",
         "description": "Fires when a tab is updated.",
         "parameters": [
           {"type": "integer", "name": "tabId", "minimum": 0},
           {
             "type": "object",
             "name": "changeInfo",
+            "description": "Lists the changes to the state of the tab that was updated.",
             "properties": {
               "status": {
                 "type": "string",
                 "description": "The status of the tab. Can be either <em>loading</em> or <em>complete</em>."
               },
               "url": {
                 "type": "string",
                 "optional": true,
                 "description": "Only specified if the tab's URL changed."
               }
             }
+          },
+          {
+            "$ref": "Tab",
+            "name": "tab",
+            "description": "Gives the state of the tab that was updated."
           }
         ]
       },
       {
         "name": "onMoved",
         "type": "function",
         "description": "Fires when a tab is moved within a window. Only one move event is fired, representing the tab the user directly moved. Move events are not fired for the other tabs that must move in response. This event is not fired when a tab is moved between windows. For that, see <a href='#event-onDetached'>onDetached</a>.",
         "parameters": [
           {"type": "integer", "name": "tabId", "minimum": 0},
           {
@@ skipping 711 matching lines @@
         "type": "function",
         "description": "Logs a message during internal unit testing.",
         "parameters": [
           {"type": "string", "name": "message"}
         ]
       }
     ],
     "events": []
   }
 ]