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diff --git a/storage/common/blob/shareable_file_reference.h b/storage/common/blob/shareable_file_reference.h
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+++ b/storage/common/blob/shareable_file_reference.h
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+// Copyright (c) 2012 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 STORAGE_COMMON_BLOB_SHAREABLE_FILE_REFERENCE_H_
+#define STORAGE_COMMON_BLOB_SHAREABLE_FILE_REFERENCE_H_
+
+#include <vector>
+
+#include "storage/common/blob/scoped_file.h"
+
+namespace storage {
+
+// ShareableFileReference allows consumers to share FileReference for the
+// same path if it already exists in its internal map.
+// This class is non-thread-safe and all methods must be called on a single
+// thread.
+class STORAGE_COMMON_EXPORT ShareableFileReference
+    : public base::RefCounted<ShareableFileReference> {
+ public:
+  typedef ScopedFile::ScopeOutCallback FinalReleaseCallback;
+
+  enum FinalReleasePolicy {
+    DELETE_ON_FINAL_RELEASE = ScopedFile::DELETE_ON_SCOPE_OUT,
+    DONT_DELETE_ON_FINAL_RELEASE = ScopedFile::DONT_DELETE_ON_SCOPE_OUT,
+  };
+
+  // Returns a ShareableFileReference for the given path, if no reference
+  // for this path exists returns NULL.
+  static scoped_refptr<ShareableFileReference> Get(const base::FilePath& path);
+
+  // Returns a ShareableFileReference for the given path, creating a new
+  // reference if none yet exists. If there's a pre-existing reference for
+  // the path, the policy parameter of this method is ignored.
+  static scoped_refptr<ShareableFileReference> GetOrCreate(
+      const base::FilePath& path,
+      FinalReleasePolicy policy,
+      base::TaskRunner* file_task_runner);
+
+  // Returns a ShareableFileReference for the given path of the |scoped_file|,
+  // creating a new reference if none yet exists. The ownership of |scoped_file|
+  // is passed to this reference.
+  // If there's a pre-existing reference for the path, the scope out policy
+  // and scope-out-callbacks of the given |scoped_file| is ignored.
+  // If the given scoped_file has an empty path (e.g. maybe already
+  // released) this returns NULL reference.
+  //
+  // TODO(kinuko): Make sure if this behavior is ok, we could alternatively
+  // merge callbacks to the existing one.
+  static scoped_refptr<ShareableFileReference> GetOrCreate(
+      ScopedFile scoped_file);
+
+  // The full file path.
+  const base::FilePath& path() const { return scoped_file_.path(); }
+
+  // The |callback| is fired when the final reference of this instance
+  // is released. If release policy is DELETE_ON_FINAL_RELEASE the
+  // callback task(s) is/are posted before the deletion is scheduled.
+  void AddFinalReleaseCallback(const FinalReleaseCallback& callback);
+
+ private:
+  friend class base::RefCounted<ShareableFileReference>;
+
+  ShareableFileReference(ScopedFile scoped_file);
+  ~ShareableFileReference();
+
+  ScopedFile scoped_file_;
+
+  DISALLOW_COPY_AND_ASSIGN(ShareableFileReference);
+};
+
+}  // namespace storage
+
+#endif  // STORAGE_COMMON_BLOB_SHAREABLE_FILE_REFERENCE_H_