[fsp] Simplify browser tests by extracting the common code.

chrome/test/data/extensions/api_test/file_system_provider/test_util/test_util.js

+// Copyright 2014 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.
+
+'use strict';
+
+// Namespace for testing utilities.
+var test_util = {};
+
+/**
+ * @type {string}
+ * @const
+ */
+test_util.FILE_SYSTEM_ID = 'vanilla.txt';
+
+/**
+ * @type {string}
+ * @const
+ */
+test_util.FILE_SYSTEM_NAME = 'Vanilla';
+
+/**
+ * @type {FileSystem}
+ */
+test_util.fileSystem = null;
+
+/**
+ * Gets volume information for the provided file system.
+ *
+ * @param {string} fileSystemId Id of the provided file system.
+ * @param {function(Object)} callback Callback to be called on result, with the
+ *     volume information object in case of success, or null if not found.
+ */
+test_util.getVolumeInfo = function(fileSystemId, callback) {
+  chrome.fileBrowserPrivate.getVolumeMetadataList(function(volumeList) {
+    for (var i = 0; i < volumeList.length; i++) {
+      if (volumeList[i].extensionId == chrome.runtime.id &&
+          volumeList[i].fileSystemId == fileSystemId) {
+        callback(volumeList[i]);
+        return;
+      }
+    }
+    callback(null);
+  });
+};
+
+/**
+ * Mounts a testing file system and calls the callback in case of a success.
+ * On failure, the current test case is failed on an assertion.
+ *
+ * @param {function()} callback Success callback.
+ */
+test_util.mountFileSystem = function(callback) {
+  chrome.fileSystemProvider.mount(
+      {
+        fileSystemId: test_util.FILE_SYSTEM_ID,
+        displayName: test_util.FILE_SYSTEM_NAME
+      },
+      function() {
+        var volumeId =
+            'provided:' + chrome.runtime.id + '-' + test_util.FILE_SYSTEM_ID +
+            '-user';
+
+        test_util.getVolumeInfo(test_util.FILE_SYSTEM_ID, function(volumeInfo) {
+          chrome.test.assertTrue(!!volumeInfo);
+          chrome.fileBrowserPrivate.requestFileSystem(
+              volumeInfo.volumeId,
+              function(inFileSystem) {
+                chrome.test.assertTrue(!!inFileSystem);
+                test_util.fileSystem = inFileSystem;
+                callback();
+              });
+        });
+      }, function() {
+        chrome.test.fail();
+      });
+};