Add drive::FileSystem::GetFileByPathForSaving().

chrome/browser/chromeos/drive/file_system_interface.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_CHROMEOS_DRIVE_FILE_SYSTEM_INTERFACE_H_
 #define CHROME_BROWSER_CHROMEOS_DRIVE_FILE_SYSTEM_INTERFACE_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 300 matching lines @@
   // |callback| must not be null.
   virtual void Pin(const base::FilePath& file_path,
                    const FileOperationCallback& callback) = 0;
 
   // Unpins a file at |file_path|.
   //
   // |callback| must not be null.
   virtual void Unpin(const base::FilePath& file_path,
                      const FileOperationCallback& callback) = 0;
 
-  // Gets |file_path| from the file system. The file entry represented by
-  // |file_path| needs to be present in in-memory representation of the file
-  // system in order to be retrieved. If the file is not cached, the file
-  // will be downloaded through GData API or Drive V2 API.
+  // Makes sure that |file_path| in the file system is available in the local
+  // cache. If the file is not cached, the file will be downloaded. The entry
+  // needs to be present in the file system.
   //
-  // |callback| must not be null.
+  // Returns the cache path and entry info to |callback|. It must not be null.
   virtual void GetFileByPath(const base::FilePath& file_path,
                              const GetFileCallback& callback) = 0;
 
+  // Makes sure that |file_path| in the file system is available in the local
+  // cache, and mark it as dirty. The next modification to the cache file is
+  // watched and is automatically uploaded to the server. If the entry is not
+  // present in the file system, it is created.
+  //
+  // Returns the cache path and entry info to |callback|. It must not be null.
+  virtual void GetFileByPathForSaving(const base::FilePath& file_path,
+                                      const GetFileCallback& callback) = 0;
+
   // Gets a file by the given |file_path|.
   // Calls |initialized_callback| when either:
   //   1) The cached file (or JSON file for hosted file) is found, or
   //   2) Starting to download the file from drive server.
   // In case of 2), the given FilePath is empty, and |get_content_callback| is
   // called repeatedly with downloaded content following the
   // |initialized_callback| invocation.
   // |completion_callback| is invoked if an error is found, or the operation
   // is successfully done.
   // |initialized_callback|, |get_content_callback| and |completion_callback|
@@ skipping 80 matching lines @@
       const std::string& resource_id,
       const GetCacheEntryCallback& callback) = 0;
 
   // Reloads the resource metadata from the server.
   virtual void Reload() = 0;
 };
 
 }  // namespace drive
 
 #endif  // CHROME_BROWSER_CHROMEOS_DRIVE_FILE_SYSTEM_INTERFACE_H_