Fix filesystem API file_handlers to work for drive on ChromeOS.

webkit/fileapi/mount_points.h

Index: webkit/fileapi/mount_points.h
diff --git a/webkit/fileapi/mount_points.h b/webkit/fileapi/mount_points.h
index 7fcc2314c8462d72112a09904a27260b37514a8f..bcb2995bad60c0c7a2dc87e7d336825d6a32e50b 100644
--- a/webkit/fileapi/mount_points.h
+++ b/webkit/fileapi/mount_points.h
@@ -88,6 +88,19 @@ class WEBKIT_STORAGE_EXPORT MountPoints {
                                 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);
 };