Implement chrome.fileSystem.requestFileSystem().

chrome/browser/chromeos/file_manager/external_filesystem_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 "base/bind.h"
 #include "base/files/file_path.h"
 #include "base/files/file_util.h"
 #include "base/files/scoped_temp_dir.h"
 #include "base/path_service.h"
 #include "chrome/browser/browser_process.h"
@@ skipping 470 matching lines @@
   void AddTestMountPoint() override {
     EXPECT_TRUE(
         content::BrowserContext::GetMountPoints(browser()->profile())
             ->RegisterFileSystem(kRestrictedMountPointName,
                                  storage::kFileSystemTypeRestrictedNativeLocal,
                                  storage::FileSystemMountOption(),
                                  mount_point_dir_));
     VolumeManager::Get(browser()->profile())
         ->AddVolumeInfoForTesting(mount_point_dir_, VOLUME_TYPE_TESTING,
                                   chromeos::DEVICE_TYPE_UNKNOWN,
-                                  false /* read_only */);
+                                  true /* read_only */);
   }
 
  private:
   base::ScopedTempDir tmp_dir_;
   base::FilePath mount_point_dir_;
 };
 
 // Tests for a drive file system.
 class DriveFileSystemExtensionApiTest : public FileSystemExtensionApiTestBase {
  public:
@@ skipping 352 matching lines @@
                        AppFileHandlerMulti) {
   EXPECT_TRUE(
       RunFileSystemExtensionApiTest("file_browser/app_file_handler_multi",
                                     FILE_PATH_LITERAL("manifest.json"),
                                     "",
                                     FLAGS_NONE))
       << message_;
 }
 }  // namespace
 }  // namespace file_manager