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

webkit/tools/test_shell/simple_file_system.cc

 // 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.
 
 #include "webkit/tools/test_shell/simple_file_system.h"
 
 #include "base/file_path.h"
 #include "base/message_loop_proxy.h"
 #include "base/time.h"
 #include "third_party/WebKit/WebKit/chromium/public/WebFileInfo.h"
@@ skipping 74 matching lines @@
 
   virtual void DidOpenFileSystem(const string16&, const FilePath&) {
     NOTREACHED();
   }
 
   virtual void DidFail(base::PlatformFileError error_code) {
     callbacks_->didFail(PlatformFileErrorToWebFileError(error_code));
     file_system_->RemoveCompletedOperation(request_id_);
   }
 
+  virtual void DidWrite(int64, bool, fileapi::FileSystemOperation*) {
+    NOTREACHED();
+  }
+
  private:
   SimpleFileSystem* file_system_;
   WebFileSystemCallbacks* callbacks_;
   int request_id_;
 };
 
 } // namespace
 
 SimpleFileSystem::~SimpleFileSystem() {
   // Drop all the operations.
@@ skipping 77 matching lines @@
   fileapi::FileSystemOperation* operation = new fileapi::FileSystemOperation(
       dispatcher, base::MessageLoopProxy::CreateForCurrentThread());
   int32 request_id = operations_.Add(operation);
   dispatcher->set_request_id(request_id);
   return operation;
 }
 
 void SimpleFileSystem::RemoveCompletedOperation(int request_id) {
   operations_.Remove(request_id);
 }