[SystemInfo API] Implement storage.getAvailableCapacity API

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

Index: chrome/test/data/extensions/api_test/system/storage/test_storage_api.js
diff --git a/chrome/test/data/extensions/api_test/system/storage/test_storage_api.js b/chrome/test/data/extensions/api_test/system/storage/test_storage_api.js
index 594f2bcf99899fdfb9d75f83506cfcb5f135aed0..8926aece48d32ac87cc8b53549b501c3c37998bc 100644
--- a/chrome/test/data/extensions/api_test/system/storage/test_storage_api.js
+++ b/chrome/test/data/extensions/api_test/system/storage/test_storage_api.js
@@ -8,13 +8,16 @@
 // Testing data should be the same as |kTestingData| in
 // system_storage_apitest.cc.
 var testData = [
-  { id:"", name: "0xbeaf", type: "removable", capacity: 4098 },
-  { id:"", name: "/home", type: "fixed", capacity: 4098 },
-  { id:"", name: "/data", type: "fixed", capacity: 10000 }
+  { id:"", name: "0xbeaf", type: "removable", capacity: 4098,
+    availableCapacity: 1},
+  { id:"", name: "/home", type: "fixed", capacity: 4098,
+    availableCapacity: 2},
+  { id:"", name: "/data", type: "fixed", capacity: 10000,
+    availableCapacity: 3}
 ];
 
 chrome.test.runTests([
-  function testGet() {
+  function testGetInfo() {
     chrome.system.storage.getInfo(chrome.test.callbackPass(function(units) {
       chrome.test.assertTrue(units.length == 3);
       for (var i = 0; i < units.length; ++i) {
@@ -24,5 +27,23 @@ chrome.test.runTests([
         chrome.test.assertEq(testData[i].capacity, units[i].capacity);
       }
     }));
+  },
+  function testGetAvailableCapacity() {
+    chrome.system.storage.getInfo(chrome.test.callbackPass(function(units) {
+      chrome.test.assertTrue(units.length == 3);
+      // Record all storage devices' |id| in testData.
+      for (var i = 0; i < units.length; ++i)
+        testData[i].id = units[i].id;
+      for (var i = 0; i < units.length; ++i) {
+        chrome.system.storage.getAvailableCapacity(units[i].id, function(info) {
+          for (var j = 0; j < units.length; ++j) {
+            if (info.id == testData[j].id) {
+              chrome.test.assertEq(testData[j].availableCapacity,
+                                   info.availableCapacity);
+            }
+          }
+        });
+      }
+    }));
   }
 ]);