Fix filesystem API file_handlers to work for drive on ChromeOS.

webkit/fileapi/mount_points.h

 // Copyright (c) 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_FILEAPI_MOUNT_POINTS_H_
 #define WEBKIT_FILEAPI_MOUNT_POINTS_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 70 matching lines @@
   // Returns false if the given virtual_path cannot be cracked.
   //
   // Note that |path| is set to empty paths if the filesystem type is isolated
   // and |virtual_path| has no <relative_path> part (i.e. pointing to the
   // virtual root).
   virtual bool CrackVirtualPath(const base::FilePath& virtual_path,
                                 std::string* mount_name,
                                 FileSystemType* type,
                                 base::FilePath* path) const = 0;
 
+  // Converts a path on a registered file system to virtual path relative to the
+  // file system root. E.g. if 'Downloads' file system is mapped to
+  // '/usr/local/home/Downloads', and |absolute| path is set to
+  // '/usr/local/home/Downloads/foo', the method will set |virtual_path| to
+  // 'Downloads/foo'.
+  // Returns false if the path cannot be resolved (e.g. if the path is not
+  // part of any registered filesystem or MountPoints implementation does not
+  // support conversion from full to virtual path).
+  //
+  // Returned virtual_path will have normalized path separators.
+  virtual bool GetVirtualPath(const base::FilePath& full_path,
+                              base::FilePath* virtual_path) const = 0;
+
  private:
   DISALLOW_COPY_AND_ASSIGN(MountPoints);
 };
 
 }  // namespace fileapi
 
 #endif  // WEBKIT_FILEAPI_MOUNT_POINTS_H_