gdata: Make callback parameter mandatory for GetEntryInfo family

chrome/browser/chromeos/gdata/gdata_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_GDATA_GDATA_FILE_SYSTEM_INTERFACE_H_
 #define CHROME_BROWSER_CHROMEOS_GDATA_GDATA_FILE_SYSTEM_INTERFACE_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 119 matching lines @@
   // Notifies the file system is going to be unmounted.
   virtual void NotifyFileSystemToBeUnmounted() = 0;
 
   // Checks for updates on the server.
   virtual void CheckForUpdates() = 0;
 
   // Finds an entry (file or directory) by using |resource_id|. This call
   // does not initiate content refreshing.
   //
   // Can be called from UI/IO thread. |callback| is run on the calling thread.
+  // |callback| must not be null.
   virtual void GetEntryInfoByResourceId(
       const std::string& resource_id,
       const GetEntryInfoWithFilePathCallback& callback) = 0;
 
   // Initiates transfer of |remote_src_file_path| to |local_dest_file_path|.
   // |remote_src_file_path| is the virtual source path on the gdata file system.
   // |local_dest_file_path| is the destination path on the local file system.
   //
   // Must be called from *UI* thread. |callback| is run on the calling thread.
   // |callback| must not be null.
@@ skipping 145 matching lines @@
   // Can be called from UI/IO thread. |callback| and is run on the calling
   // thread.
   virtual void UpdateFileByResourceId(
       const std::string& resource_id,
       const FileOperationCallback& callback) = 0;
 
   // Finds an entry (a file or a directory) by |file_path|. This call will also
   // retrieve and refresh file system content from server and disk cache.
   //
   // Can be called from UI/IO thread. |callback| is run on the calling thread.
+  // |callback| must not be null.
   virtual void GetEntryInfoByPath(const FilePath& file_path,
                                   const GetEntryInfoCallback& callback) = 0;
 
   // Finds and reads a directory by |file_path|. This call will also retrieve
   // and refresh file system content from server and disk cache.
   //
   // Can be called from UI/IO thread. |callback| is run on the calling thread.
+  // |callback| must not be null.
   virtual void ReadDirectoryByPath(
       const FilePath& file_path,
       const ReadDirectoryWithSettingCallback& callback) = 0;
 
   // Requests a refresh of the directory pointed by |file_path| (i.e. fetches
   // the latest metadata of files in the target directory).
   //
   // In particular, this function is used to get the latest thumbnail
   // URLs. Thumbnail URLs change periodically even if contents of files are
   // not changed, hence we should get the new thumbnail URLs manually if we
@@ skipping 35 matching lines @@
                                const FilePath& virtual_dir_path,
                                scoped_ptr<DocumentEntry> entry,
                                const FilePath& file_content_path,
                                GDataCache::FileOperationType cache_operation,
                                const base::Closure& callback) = 0;
 };
 
 }  // namespace gdata
 
 #endif  // CHROME_BROWSER_CHROMEOS_GDATA_GDATA_FILE_SYSTEM_INTERFACE_H_