Add FileSystemMountPointProvider::CreateFileReader() which returns appropriate Reader instance

webkit/fileapi/sandbox_mount_point_provider.h

 // 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 WEBKIT_FILEAPI_SANDBOX_MOUNT_POINT_PROVIDER_H_
 #define WEBKIT_FILEAPI_SANDBOX_MOUNT_POINT_PROVIDER_H_
 
 #include <set>
 #include <string>
 #include <vector>
@@ skipping 75 matching lines @@
   virtual std::vector<FilePath> GetRootDirectories() const OVERRIDE;
   virtual FileSystemFileUtil* GetFileUtil() OVERRIDE;
   virtual FilePath GetPathForPermissionsCheck(const FilePath& virtual_path)
       const OVERRIDE;
   virtual FileSystemOperationInterface* CreateFileSystemOperation(
       const GURL& origin_url,
       FileSystemType file_system_type,
       const FilePath& virtual_path,
       base::MessageLoopProxy* file_proxy,
       FileSystemContext* context) const OVERRIDE;
+  virtual webkit_blob::FileReader* CreateFileReader(
+    const GURL& url,
+    int64 offset,
+    base::MessageLoopProxy* file_proxy,
+    FileSystemContext* context) const OVERRIDE;
 
   FilePath old_base_path() const;
   FilePath new_base_path() const;
   FilePath renamed_old_base_path() const;
 
   // Returns an origin enumerator of this provider.
   // This method can only be called on the file thread.
   OriginEnumerator* CreateOriginEnumerator() const;
 
   // Gets a base directory path of the sandboxed filesystem that is
@@ skipping 72 matching lines @@
 
   // Acccessed only on the file thread.
   std::set<GURL> visited_origins_;
 
   DISALLOW_COPY_AND_ASSIGN(SandboxMountPointProvider);
 };
 
 }  // namespace fileapi
 
 #endif  // WEBKIT_FILEAPI_SANDBOX_MOUNT_POINT_PROVIDER_H_