[fsp] Add support for truncating files.

chrome/browser/chromeos/file_system_provider/provided_file_system.cc

 // Copyright 2014 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 "chrome/browser/chromeos/file_system_provider/provided_file_system.h"
 
 #include "base/debug/trace_event.h"
 #include "base/files/file.h"
 #include "chrome/browser/chromeos/file_system_provider/notification_manager.h"
 #include "chrome/browser/chromeos/file_system_provider/operations/close_file.h"
 #include "chrome/browser/chromeos/file_system_provider/operations/copy_entry.h"
 #include "chrome/browser/chromeos/file_system_provider/operations/create_directory.h"
 #include "chrome/browser/chromeos/file_system_provider/operations/create_file.h"
 #include "chrome/browser/chromeos/file_system_provider/operations/delete_entry.h"
 #include "chrome/browser/chromeos/file_system_provider/operations/get_metadata.h"
 #include "chrome/browser/chromeos/file_system_provider/operations/move_entry.h"
 #include "chrome/browser/chromeos/file_system_provider/operations/open_file.h"
 #include "chrome/browser/chromeos/file_system_provider/operations/read_directory.h"
 #include "chrome/browser/chromeos/file_system_provider/operations/read_file.h"
+#include "chrome/browser/chromeos/file_system_provider/operations/truncate.h"
 #include "chrome/browser/chromeos/file_system_provider/operations/unmount.h"
 #include "chrome/browser/chromeos/file_system_provider/request_manager.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/common/extensions/api/file_system_provider.h"
 #include "extensions/browser/event_router.h"
 
 namespace net {
 class IOBuffer;
 }  // namespace net
 
@@ skipping 176 matching lines @@
           scoped_ptr<RequestManager::HandlerInterface>(
               new operations::MoveEntry(event_router_,
                                         file_system_info_,
                                         source_path,
                                         target_path,
                                         callback)))) {
     callback.Run(base::File::FILE_ERROR_SECURITY);
   }
 }
 
+void ProvidedFileSystem::Truncate(
+    const base::FilePath& file_path,
+    int64 length,
+    const fileapi::AsyncFileUtil::StatusCallback& callback) {
+  if (!request_manager_.CreateRequest(
+          TRUNCATE,
+          scoped_ptr<RequestManager::HandlerInterface>(
+              new operations::Truncate(event_router_,
+                                       file_system_info_,
+                                       file_path,
+                                       length,
+                                       callback)))) {
+    callback.Run(base::File::FILE_ERROR_SECURITY);
+  }
+}
+
 const ProvidedFileSystemInfo& ProvidedFileSystem::GetFileSystemInfo() const {
   return file_system_info_;
 }
 
 RequestManager* ProvidedFileSystem::GetRequestManager() {
   return &request_manager_;
 }
 
 base::WeakPtr<ProvidedFileSystemInterface> ProvidedFileSystem::GetWeakPtr() {
   return weak_ptr_factory_.GetWeakPtr();
 }
 
 }  // namespace file_system_provider
 }  // namespace chromeos