fileapi: Add modification time check for FileSystemFileStreamReader

webkit/fileapi/file_system_context.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 WEBKIT_FILEAPI_FILE_SYSTEM_CONTEXT_H_
 #define WEBKIT_FILEAPI_FILE_SYSTEM_CONTEXT_H_
 
 #include <map>
 #include <string>
 
@@ skipping 129 matching lines @@
   // Creates a new FileSystemOperation instance by cracking
   // the given filesystem URL |url| to get an appropriate MountPointProvider
   // and calling the provider's corresponding CreateFileSystemOperation method.
   // The resolved MountPointProvider could perform further specialization
   // depending on the filesystem type pointed by the |url|.
   FileSystemOperation* CreateFileSystemOperation(
       const FileSystemURL& url,
       base::PlatformFileError* error_code);
 
   // Creates new FileStreamReader instance to read a file pointed by the given
-  // filesystem URL |url| starting from |offset|.
+  // filesystem URL |url| starting from |offset|. |expected_modification_time|
+  // specifies the expected last modification if the value is non-null, the
+  // reader will check the underlying file's actual modification time to see if
+  // the file has been modified, and if it does any succeeding read operations
+  // should fail with ERR_UPLOAD_FILE_CHANGED error.
   // This method internally cracks the |url|, get an appropriate
   // MountPointProvider for the URL and call the provider's CreateFileReader.
   // The resolved MountPointProvider could perform further specialization
   // depending on the filesystem type pointed by the |url|.
   webkit_blob::FileStreamReader* CreateFileStreamReader(
       const FileSystemURL& url,
-      int64 offset);
+      int64 offset,
+      const base::Time& expected_modification_time);
 
   // Register a filesystem provider. The ownership of |provider| is
   // transferred to this instance.
   void RegisterMountPointProvider(FileSystemType type,
                                   FileSystemMountPointProvider* provider);
 
   FileSystemTaskRunners* task_runners() { return task_runners_.get(); }
 
   LocalFileChangeTracker* change_tracker() { return change_tracker_.get(); }
   void SetLocalFileChangeTracker(scoped_ptr<LocalFileChangeTracker> tracker);
@@ skipping 36 matching lines @@
 
 struct DefaultContextDeleter {
   static void Destruct(const FileSystemContext* context) {
     context->DeleteOnCorrectThread();
   }
 };
 
 }  // namespace fileapi
 
 #endif  // WEBKIT_FILEAPI_FILE_SYSTEM_CONTEXT_H_