Add systemInfo.cpu.onUpdated event implementation.

chrome/test/data/extensions/api_test/systeminfo/cpu/test_cpu_api.js

+// 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.
+
+// systeminfo.cpu api test
+// browser_tests.exe --gtest_filter=SystemInfoCpuApiTest.*
+
+chrome.systemInfo = chrome.experimental.systemInfo;
+
+var userStep = 3;
+var kernelStep = 2;
+var idleStep = 1;
+function calculateUsage(count) {
+  return (100 - idleStep * 100/(userStep + kernelStep + idleStep));
+}
+
+chrome.test.runTests([
+  function testGet() {
+    for(var i = 0; i < 20; ++i) {
+      chrome.systemInfo.cpu.get(chrome.test.callbackPass(function(result) {
+        chrome.test.assertEq(4, result.numOfProcessors);
+        chrome.test.assertEq("x86", result.archName);
+        chrome.test.assertEq("unknown", result.modelName);
+      }));
+    }
+  },
+  function testUpdatedEvent() {

[benwells, 2012/09/21 08:19:50]

Blank line above here.

[Hongbo Min, 2012/09/21 09:00:23]

Done.

+    var numOfUpdatedEvent = 0;
+    var doneUpdatedEvent = chrome.test.listenForever(
+      chrome.systemInfo.cpu.onUpdated,
+      function listener(updateInfo) {

[benwells, 2012/09/21 08:19:50]

Indent this two block two more spaces.

[Hongbo Min, 2012/09/21 09:00:23]

Done.

+        var expectedUsage = calculateUsage(numOfUpdatedEvent);
+        chrome.test.assertEq(updateInfo.averageUsage, expectedUsage);
+        chrome.test.assertEq(updateInfo.usagePerProcessor.length, 4);
+        for (var i = 0; i < updateInfo.usagePerProcessor.length; ++i) {

[benwells, 2012/09/21 08:19:50]

Can drop these curly braces.

[Hongbo Min, 2012/09/21 09:00:23]

Done.

+          chrome.test.assertEq(updateInfo.usagePerProcessor[i], expectedUsage);
+        }
+        if (++numOfUpdatedEvent > 5)
+          doneUpdatedEvent();
+      });
+  }
+]);
+