Flesh out more extensions tab api (added removeTab, updateTab)

chrome/renderer/resources/extension_process_bindings.js

 var chromium;
 (function() {
   if (!chromium)
     chromium = {};
 
   // callback handling
   var callbacks = [];
   chromium._dispatchCallback = function(callbackId, str) {
-    callbacks[callbackId](goog.json.parse(str));
-    delete callbacks[callbackId];
+    try {
+      if (str) {
+        callbacks[callbackId](goog.json.parse(str));
+      } else {
+        callbacks[callbackId]();
+      }
+    } finally {
+      delete callbacks[callbackId];
+    }
   };
 
   // Send an API request and optionally register a callback.
   function sendRequest(request, args, callback) {
     var sargs = goog.json.serialize(args);
     var callbackId = -1;
     if (callback) {
       native function GetNextCallbackId();
       callbackId = GetNextCallbackId();
       callbacks[callbackId] = callback;
     }
     request(sargs, callbackId);
   }
 
   // Tabs
   chromium.tabs = {};
   // TODO(aa): This should eventually take an optional windowId param.
   chromium.tabs.getTabsForWindow = function(callback) {
     native function GetTabsForWindow();
     sendRequest(GetTabsForWindow, null, callback);
   };
+  chromium.tabs.getTab = function(tabId, callback) {
+    native function GetTab();
+    sendRequest(GetTab, tabId, callback);
+  };
   chromium.tabs.createTab = function(tab, callback) {
     native function CreateTab();
     sendRequest(CreateTab, tab, callback);
   };
+  chromium.tabs.updateTab = function(tab) {
+    native function UpdateTab();
+    sendRequest(UpdateTab, tab);
+  };
+  chromium.tabs.removeTab = function(tabId) {
+    native function RemoveTab();
+    sendRequest(RemoveTab, tabId);
+  };
 })();