Add the basic code skeleton for system info event router

chrome/test/data/extensions/api_test/systeminfo/storage/test_storage_api.js

Index: chrome/test/data/extensions/api_test/systeminfo/storage/test_storage_api.js
diff --git a/chrome/test/data/extensions/api_test/systeminfo/storage/test_storage_api.js b/chrome/test/data/extensions/api_test/systeminfo/storage/test_storage_api.js
index 787ca408abbe912b1aefdc209792a16125c5fe7b..f0fc3f9c2547427b48a87a65e4730e5ec997c696 100644
--- a/chrome/test/data/extensions/api_test/systeminfo/storage/test_storage_api.js
+++ b/chrome/test/data/extensions/api_test/systeminfo/storage/test_storage_api.js
@@ -7,7 +7,7 @@
 chrome.systemInfo = chrome.experimental.systemInfo;
 
 chrome.test.runTests([
-  function testGet() {
+  function testStorageGet() {
     chrome.systemInfo.storage.get(chrome.test.callbackPass(function(info) {
       chrome.test.assertTrue(info.units.length == 1);
       var unit = info.units[0];
@@ -16,5 +16,19 @@ chrome.test.runTests([
       chrome.test.assertTrue(unit.capacity == 4098);
       chrome.test.assertTrue(unit.availableCapacity == 1024);
     }));
-  }
+  },
+  function testChangedEvent() {
+    var numOfChangedEvent = 0;
+    var base = 10000;
+    var step = 10;
+    var doneChangedEvent = chrome.test.listenForever(
+      chrome.systemInfo.storage.onAvailableCapacityChanged,
+      function listener(changedInfo) {
+        chrome.test.assertTrue(changedInfo.id == "/dev/sda1");
+        chrome.test.assertTrue(
+          changedInfo.availableCapacity == (base - numOfChangedEvent*step));
+        if (++ numOfChangedEvent > 5)
+          doneChangedEvent();
+      });
+  },
 ]);