Reject filesystem root entries as args for chrome.fileSystem functions.

chrome/browser/extensions/api/file_system/file_system_apitest.cc

 // 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.
 
 #include "apps/saved_files_service.h"
 #include "base/file_util.h"
 #include "base/path_service.h"
 #include "build/build_config.h"
 #include "chrome/browser/apps/app_browsertest_util.h"
 #include "chrome/browser/chrome_notification_types.h"
@@ skipping 535 matching lines @@
 IN_PROC_BROWSER_TEST_F(FileSystemApiTest,
     FileSystemApiGetWritableWithWriteTest) {
   base::FilePath test_file = TempFilePath("writable.txt", true);
   ASSERT_FALSE(test_file.empty());
   FileSystemChooseEntryFunction::SkipPickerAndAlwaysSelectPathForTest(
       &test_file);
   ASSERT_TRUE(RunPlatformAppTest(
       "api_test/file_system/get_writable_file_entry_with_write")) << message_;
 }
 
+IN_PROC_BROWSER_TEST_F(FileSystemApiTest,
+                       FileSystemApiGetWritableRootEntryTest) {
+  base::FilePath test_file = TempFilePath("writable.txt", true);
+  ASSERT_FALSE(test_file.empty());
+  FileSystemChooseEntryFunction::SkipPickerAndAlwaysSelectPathForTest(
+      &test_file);
+  ASSERT_TRUE(RunPlatformAppTest(
+      "api_test/file_system/get_writable_root_entry")) << message_;
+}
+
 IN_PROC_BROWSER_TEST_F(FileSystemApiTest, FileSystemApiIsWritableTest) {
   base::FilePath test_file = TempFilePath("writable.txt", true);
   ASSERT_FALSE(test_file.empty());
   FileSystemChooseEntryFunction::SkipPickerAndAlwaysSelectPathForTest(
       &test_file);
   ASSERT_TRUE(RunPlatformAppTest("api_test/file_system/is_writable_file_entry"))
       << message_;
 }
 
 IN_PROC_BROWSER_TEST_F(FileSystemApiTest,
@@ skipping 61 matching lines @@
   AppInstallObserver observer(
       base::Bind(AddSavedEntry,
                  test_directory,
                  true,
                  apps::SavedFilesService::Get(profile())));
   ASSERT_TRUE(RunPlatformAppTest("api_test/file_system/restore_directory"))
       << message_;
 }
 
 }  // namespace extensions