Add automated test for chrome.onFileSynced JavsScript event.

chrome/test/data/extensions/api_test/sync_file_system/on_file_synced/test.js

Index: chrome/test/data/extensions/api_test/sync_file_system/on_file_synced/test.js
diff --git a/chrome/test/data/extensions/api_test/sync_file_system/on_sync_state_changed/test.js b/chrome/test/data/extensions/api_test/sync_file_system/on_file_synced/test.js
similarity index 52%
copy from chrome/test/data/extensions/api_test/sync_file_system/on_sync_state_changed/test.js
copy to chrome/test/data/extensions/api_test/sync_file_system/on_file_synced/test.js
index ff200478f422f7088a5b3bee65f09241705b36ca..39e03d8003745c2e549e710e90a385b15575da43 100644
--- a/chrome/test/data/extensions/api_test/sync_file_system/on_sync_state_changed/test.js
+++ b/chrome/test/data/extensions/api_test/sync_file_system/on_file_synced/test.js
@@ -3,14 +3,13 @@
 // found in the LICENSE file.
 
 function setupListener() {
-  chrome.syncFileSystem.onSyncStateChanged.addListener(checkEventReceived);
+  chrome.syncFileSystem.onFileSynced.addListener(fileSyncEventReceived);
   chrome.syncFileSystem.requestFileSystem('drive', function() {});
 }
 
-function checkEventReceived(syncState) {
-  chrome.test.assertEq("drive", syncState.service_name);
-  chrome.test.assertEq("running", syncState.state);
-  chrome.test.assertEq("Test event description.", syncState.description);
+function fileSyncEventReceived(file_entry_path, sync_operation_result) {
+  chrome.test.assertEq("foo", file_entry_path);
+  chrome.test.assertEq("added", sync_operation_result);
   chrome.test.succeed();
 }