Split file_observers.h into three files for each class

webkit/browser/fileapi/file_update_observer.h

+// Copyright 2013 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_BROWSER_FILEAPI_FILE_UPDATE_OBSERVER_H_
+#define WEBKIT_BROWSER_FILEAPI_FILE_UPDATE_OBSERVER_H_
+
+#include "base/basictypes.h"
+
+namespace fileapi {
+
+class FileSystemURL;
+
+// An abstract interface to observe update operations.
+//
+// OnStartUpdate and OnEndUpdate are called once for each target url
+// before and after following operations regardless of whether the operation
+// is made recursively or not (i.e. StartUpdate() will be called only once
+// for destination url regardless of whether it is recursive copy or not):
+//  CreateFile(), CreateDirectory(),
+//  Copy() (destination only),
+//  Move() (both for source and destination),
+//  Remove(), Write(), Truncate(), TouchFile()
+//
+// OnUpdate() is called each time the |url| is updated but works only for
+// sandboxed files (where usage is tracked).
+class FileUpdateObserver {
+ public:
+  FileUpdateObserver() {}
+  virtual ~FileUpdateObserver() {}
+
+  virtual void OnStartUpdate(const FileSystemURL& url) = 0;
+  virtual void OnUpdate(const FileSystemURL& url, int64 delta) = 0;
+  virtual void OnEndUpdate(const FileSystemURL& url) = 0;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(FileUpdateObserver);
+};
+
+}  // namespace fileapi
+
+#endif  // WEBKIT_BROWSER_FILEAPI_FILE_UPDATE_OBSERVER_H_