Don't allow multiple opens for Pepper FileSystem.

webkit/plugins/ppapi/ppb_file_system_impl.h

 // Copyright (c) 2010 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_PLUGINS_PPAPI_PPB_FILE_SYSTEM_IMPL_H_
 #define WEBKIT_PLUGINS_PPAPI_PPB_FILE_SYSTEM_IMPL_H_
 
 #include "base/basictypes.h"
 #include "base/file_path.h"
 #include "ppapi/c/dev/pp_file_info_dev.h"
@@ skipping 14 matching lines @@
 
   PPB_FileSystem_Impl(PluginInstance* instance, PP_FileSystemType_Dev type);
   virtual PPB_FileSystem_Impl* AsPPB_FileSystem_Impl();
 
   PluginInstance* instance() { return instance_; }
   PP_FileSystemType_Dev type() { return type_; }
   const FilePath& root_path() const { return root_path_; }
   void set_root_path(const FilePath& root_path) { root_path_ = root_path; }
   bool opened() const { return opened_; }
   void set_opened(bool opened) { opened_ = opened; }
+  bool called_open() const { return called_open_; }
+  void set_called_open() { called_open_ = true; }
 
  private:
   PluginInstance* instance_;
   PP_FileSystemType_Dev type_;
   FilePath root_path_;
   bool opened_;
+  bool called_open_;
 
   DISALLOW_COPY_AND_ASSIGN(PPB_FileSystem_Impl);
 };
 
 }  // namespace ppapi
 }  // namespace webkit
 
 #endif  // WEBKIT_PLUGINS_PPAPI_PPB_FILE_SYSTEM_IMPL_H_