Add width and height to chrome.tabs.Tab.

chrome/test/data/extensions/api_test/tabs/basics/tab_size.js

+// Copyright (c) 2013 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.
+
+var firstTabId;
+var firstTab;
+
+chrome.test.runTests([
+  function setupWindow() {
+    createWindow([pageUrl("a")], {}, pass(function(winId, tabIds) {
+      firstTabId = tabIds[0];
+      chrome.tabs.get(firstTabId, pass(function(tab) {
+        assertTrue(tab.width > 0);
+        assertTrue(tab.height > 0);
+        firstTab = tab;
+      }));
+    }));
+  },
+
+  function sizeAfterDuplicatingTab() {
+    chrome.tabs.duplicate(firstTabId, pass(function(tab) {
+      assertEq(firstTab.width, tab.width);
+      assertEq(firstTab.height, tab.height);
+    }));
+  }
+]);