Add tests for chrome.fileSystem app API.

chrome/browser/extensions/api/file_system/file_system_api.h

 // 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.
 
 #ifndef CHROME_BROWSER_EXTENSIONS_API_FILE_SYSTEM_FILE_SYSTEM_API_H_
 #define CHROME_BROWSER_EXTENSIONS_API_FILE_SYSTEM_FILE_SYSTEM_API_H_
 #pragma once
 
 #include "chrome/browser/extensions/extension_function.h"
 
 namespace extensions {
 
 class FileSystemGetDisplayPathFunction : public SyncExtensionFunction {
  public:
   DECLARE_EXTENSION_FUNCTION_NAME("fileSystem.getDisplayPath");
 
  protected:
   virtual ~FileSystemGetDisplayPathFunction() {}
   virtual bool RunImpl() OVERRIDE;
 };
 
 class FileSystemPickerFunction : public AsyncExtensionFunction {
+ public:
+  // Allow picker UI to be skipped in testing.
+  static void SkipPickerAndAlwaysSelectPathForTest(FilePath* path);
+  static void SkipPickerAndAlwaysCancelForTest();
+  static void StopSkippingPickerForTest();
+
  protected:
   class FilePicker;
 
   virtual ~FileSystemPickerFunction() {}
   bool ShowPicker(const FilePath& suggested_path, bool for_save);
 
  private:
   // FileSelected and FileSelectionCanceled are called by the file picker.
   void FileSelected(const FilePath& path, bool for_save);
   void FileSelectionCanceled();
@@ skipping 26 matching lines @@
   DECLARE_EXTENSION_FUNCTION_NAME("fileSystem.chooseFile");
 
  protected:
   virtual ~FileSystemChooseFileFunction() {}
   virtual bool RunImpl() OVERRIDE;
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_API_FILE_SYSTEM_FILE_SYSTEM_API_H_