Add support for persistent file access in apps.

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

Index: chrome/browser/extensions/api/file_system/file_system_api.h
diff --git a/chrome/browser/extensions/api/file_system/file_system_api.h b/chrome/browser/extensions/api/file_system/file_system_api.h
index 0dad0c025d92e9ecfad31c502333abdc6307ddd8..154c6d0cd5f7d14e021c57af94f8639155cf35c4 100644
--- a/chrome/browser/extensions/api/file_system/file_system_api.h
+++ b/chrome/browser/extensions/api/file_system/file_system_api.h
@@ -44,6 +44,15 @@ class FileSystemEntryFunction : public AsyncExtensionFunction {
   void RegisterFileSystemAndSendResponse(const base::FilePath& path,
                                          EntryType entry_type);
 
+  // This will finish the choose file process. This is either called directly
+  // from FileSelected, or from CreateFileIfNecessary. It is called on the UI
+  // thread. |id_override| specifies the id to send in the response instead of
+  // the generated id.

[koz (OOO until 15th September), 2013/05/23 07:32:22]

Could you expand a bit on why it would be useful to override the generated id?

[Sam McNally, 2013/05/24 00:46:03]

Done.

+  void RegisterFileSystemAndSendResponseWithIdOverride(
+      const base::FilePath& path,
+      EntryType entry_type,
+      const std::string& id_override);
+
   // called on the UI thread if there is a problem checking a writable file.
   void HandleWritableFileError();
 };
@@ -115,6 +124,38 @@ class FileSystemChooseEntryFunction : public FileSystemEntryFunction {
   base::FilePath initial_path_;
 };
 
+class FileSystemRetainEntryFunction : public SyncExtensionFunction {
+ public:
+  DECLARE_EXTENSION_FUNCTION("fileSystem.retainEntry", FILESYSTEM_RETAINENTRY)
+
+ protected:
+  virtual ~FileSystemRetainEntryFunction() {}
+  virtual bool RunImpl() OVERRIDE;
+
+ private:
+  // Retains the file entry referenced by |entry_id| in apps::SavedFilesService.
+  // |entry_id| must refer to an entry in an isolated file system.
+  bool RetainFileEntry(const std::string& entry_id);
+};
+
+class FileSystemIsRestorableFunction : public SyncExtensionFunction {
+ public:
+  DECLARE_EXTENSION_FUNCTION("fileSystem.isRestorable", FILESYSTEM_ISRESTORABLE)
+
+ protected:
+  virtual ~FileSystemIsRestorableFunction() {}
+  virtual bool RunImpl() OVERRIDE;
+};
+
+class FileSystemRestoreEntryFunction : public FileSystemEntryFunction {
+ public:
+  DECLARE_EXTENSION_FUNCTION("fileSystem.restoreEntry", FILESYSTEM_RESTOREENTRY)
+
+ protected:
+  virtual ~FileSystemRestoreEntryFunction() {}
+  virtual bool RunImpl() OVERRIDE;
+};
+
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_API_FILE_SYSTEM_FILE_SYSTEM_API_H_