This is the IPC and bits of the browser backend for FileWriter. The rest of...

webkit/fileapi/file_system_operation.h

 // Copyright (c) 2010 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_OPERATION_H_
 #define WEBKIT_FILEAPI_FILE_SYSTEM_OPERATION_H_
 
 #include <vector>
 
 #include "base/file_path.h"
 #include "base/file_util_proxy.h"
 #include "base/message_loop_proxy.h"
 #include "base/platform_file.h"
 #include "base/ref_counted.h"
 #include "base/scoped_callback_factory.h"
 #include "base/scoped_ptr.h"
 
+class GURL;
+
 namespace fileapi {
 
 class FileSystemCallbackDispatcher;
 
 // This class is designed to serve one-time file system operation per instance.
 // Only one method(CreateFile, CreateDirectory, Copy, Move, DirectoryExists,
 // GetMetadata, ReadDirectory and Remove) may be called during the lifetime of
 // this object and it should be called no more than once.
 class FileSystemOperation {
  public:
@@ skipping 20 matching lines @@
   void DirectoryExists(const FilePath& path);
 
   void FileExists(const FilePath& path);
 
   void GetMetadata(const FilePath& path);
 
   void ReadDirectory(const FilePath& path);
 
   void Remove(const FilePath& path);
 
+  void Write(
+      const FilePath& path, const GURL& blob_url, int64 offset);
+
+  void Truncate(const FilePath& path, int64 length);
+
+  // Used to attempt to cancel the current operation.  This currently does
+  // nothing for any operation other than Write().
+  void Cancel();
+
  protected:
   // Proxy for calling file_util_proxy methods.
   scoped_refptr<base::MessageLoopProxy> proxy_;
 
  private:
   // Callbacks for above methods.
   void DidCreateFileExclusive(
       base::PlatformFileError rv, base::PassPlatformFile file, bool created);
 
   // Returns success even if the file already existed.
   void DidCreateFileNonExclusive(
       base::PlatformFileError rv, base::PassPlatformFile file, bool created);
 
   // Generic callback that translates platform errors to WebKit error codes.
   void DidFinishFileOperation(base::PlatformFileError rv);
 
   void DidDirectoryExists(base::PlatformFileError rv,
                           const base::PlatformFileInfo& file_info);
 
   void DidFileExists(base::PlatformFileError rv,
                      const base::PlatformFileInfo& file_info);
 
   void DidGetMetadata(base::PlatformFileError rv,
                       const base::PlatformFileInfo& file_info);
 
   void DidReadDirectory(
       base::PlatformFileError rv,
       const std::vector<base::file_util_proxy::Entry>& entries);
 
+  void DidWrite(
+      base::PlatformFileError rv,
+      int64 bytes,
+      bool complete);
+
   scoped_ptr<FileSystemCallbackDispatcher> dispatcher_;
 
   base::ScopedCallbackFactory<FileSystemOperation> callback_factory_;
 
 #ifndef NDEBUG
   // A flag to make sure we call operation only once per instance.
   bool operation_pending_;
 #endif
 
   DISALLOW_COPY_AND_ASSIGN(FileSystemOperation);
 };
 
 }  // namespace fileapi
 
 #endif  // WEBKIT_FILEAPI_FILE_SYSTEM_OPERATION_H_