(2nd try) Add a helper class that keeps per-profile information for FileSystem API

chrome/browser/file_system/file_system_dispatcher_host.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 CHROME_BROWSER_FILE_SYSTEM_FILE_SYSTEM_DISPATCHER_HOST_H_
 #define CHROME_BROWSER_FILE_SYSTEM_FILE_SYSTEM_DISPATCHER_HOST_H_
 
 #include "base/basictypes.h"
 #include "base/nullable_string16.h"
 #include "base/process.h"
 #include "base/ref_counted.h"
 #include "chrome/common/render_messages.h"
 
+class FileSystemHostContext;
 class HostContentSettingsMap;
 class Receiver;
 class ResourceMessageFilter;
 
 class FileSystemDispatcherHost
     : public base::RefCountedThreadSafe<FileSystemDispatcherHost> {
  public:
   FileSystemDispatcherHost(IPC::Message::Sender* sender,
+                           FileSystemHostContext* file_system_host_context,
                            HostContentSettingsMap* host_content_settings_map);
   void Init(base::ProcessHandle process_handle);
   void Shutdown();
 
   bool OnMessageReceived(const IPC::Message& message, bool* message_was_ok);
 
   void OnOpenFileSystem(const ViewHostMsg_OpenFileSystemRequest_Params&);
   void OnMove(
       int request_id,
       const string16& src_path,
       const string16& dest_path);
 
   // TODO(kinuko): add more methods.
 
   void Send(IPC::Message* message);
 
  private:
   void Move(const string16& src, const string16& dest, int operation_id);
 
   // The sender to be used for sending out IPC messages.
   IPC::Message::Sender* message_sender_;
 
   // The handle of this process.
   base::ProcessHandle process_handle_;
 
   bool shutdown_;
 
+  scoped_refptr<FileSystemHostContext> context_;
+
   // Used to look up permissions.
   scoped_refptr<HostContentSettingsMap> host_content_settings_map_;
 };
 
 #endif  // CHROME_BROWSER_FILE_SYSTEM_FILE_SYSTEM_DISPATCHER_HOST_H_