Add truncate and cancel for FileWriter; write and tests will come in later CL...

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"
@@ skipping 43 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 Write(const FilePath& path, const GURL& blob_url, int64 offset);
 
   void Truncate(const FilePath& path, int64 length);
 
   void TouchFile(const FilePath& path,
                  const base::Time& last_access_time,
                  const base::Time& last_modified_time);
 
-  // Used to attempt to cancel the current operation.  This currently does
-  // nothing for any operation other than Write().
-  void Cancel();
+  // Try to cancel the current operation [we support cancelling write or
+  // truncate only].  Report failure for the current operation, then tell the
+  // passed-in operation to report success.
+  void Cancel(FileSystemOperation* cancel_operation);
 
  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);
 
@@ skipping 21 matching lines @@
       base::PlatformFileError rv,
       int64 bytes,
       bool complete);
 
   void DidTouchFile(base::PlatformFileError rv);
 
   scoped_ptr<FileSystemCallbackDispatcher> dispatcher_;
 
   base::ScopedCallbackFactory<FileSystemOperation> callback_factory_;
 
+  FileSystemOperation* cancel_operation_;
+
 #ifndef NDEBUG
+  enum OperationType {
+    kOperationNone,
+    kOperationCreateFile,
+    kOperationCreateDirectory,
+    kOperationCopy,
+    kOperationMove,
+    kOperationDirectoryExists,
+    kOperationFileExists,
+    kOperationGetMetadata,
+    kOperationReadDirectory,
+    kOperationRemove,
+    kOperationWrite,
+    kOperationTruncate,
+    kOperationTouchFile,
+    kOperationCancel,
+  };
+
   // A flag to make sure we call operation only once per instance.
-  bool operation_pending_;
+  OperationType pending_operation_;
 #endif
 
   DISALLOW_COPY_AND_ASSIGN(FileSystemOperation);
 };
 
 }  // namespace fileapi
 
 #endif  // WEBKIT_FILEAPI_FILE_SYSTEM_OPERATION_H_