Add isWritableFileEntry to the fileSystem 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_
 
 #include "chrome/browser/extensions/extension_function.h"
 #include "chrome/browser/ui/select_file_dialog.h"
 
@@ skipping 36 matching lines @@
 
 class FileSystemGetWritableFileEntryFunction : public FileSystemEntryFunction {
  public:
   DECLARE_EXTENSION_FUNCTION_NAME("fileSystem.getWritableFileEntry");
 
  protected:
   virtual ~FileSystemGetWritableFileEntryFunction() {}
   virtual bool RunImpl() OVERRIDE;
 };
 
+class FileSystemIsWritableFileEntryFunction : public SyncExtensionFunction {
+ public:
+  DECLARE_EXTENSION_FUNCTION_NAME("fileSystem.isWritableFileEntry");
+
+ protected:
+  virtual ~FileSystemIsWritableFileEntryFunction() {}
+  virtual bool RunImpl() OVERRIDE;
+};
+
 class FileSystemChooseFileFunction : public FileSystemEntryFunction {
  public:
   // Allow picker UI to be skipped in testing.
   static void SkipPickerAndAlwaysSelectPathForTest(FilePath* path);
   static void SkipPickerAndAlwaysCancelForTest();
   static void StopSkippingPickerForTest();
 
   DECLARE_EXTENSION_FUNCTION_NAME("fileSystem.chooseFile");
 
  protected:
   class FilePicker;
 
   virtual ~FileSystemChooseFileFunction() {}
   virtual bool RunImpl() OVERRIDE;
   bool ShowPicker(const FilePath& suggested_path,
                   SelectFileDialog::Type picker_type,
                   EntryType entry_type);
 
  private:
   // FileSelected and FileSelectionCanceled are called by the file picker.
   void FileSelected(const FilePath& path, EntryType entry_type);
   void FileSelectionCanceled();
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_API_FILE_SYSTEM_FILE_SYSTEM_API_H_