Add GetURLForBrowserTab method to the external file system backend.

chrome/browser/chromeos/fileapi/file_system_backend_delegate.h

 // Copyright 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 CHROME_BROWSER_CHROMEOS_FILEAPI_FILE_SYSTEM_BACKEND_DELEGATE_H_
 #define CHROME_BROWSER_CHROMEOS_FILEAPI_FILE_SYSTEM_BACKEND_DELEGATE_H_
 
 #include "base/basictypes.h"
+#include "base/callback_forward.h"
 #include "base/memory/scoped_ptr.h"
 #include "webkit/common/fileapi/file_system_types.h"
 
+class GURL;
+
 namespace base {
 class Time;
 }  // namespace base
 
 namespace storage {
 class AsyncFileUtil;
 class FileSystemContext;
 class FileStreamReader;
 class FileSystemURL;
 class FileStreamWriter;
 class WatcherManager;
 }  // namespace storage
 
 namespace storage {
 class FileStreamReader;
 }  // namespace storage
 
 namespace chromeos {
 
 // This is delegate interface to inject the implementation of the some methods
 // of FileSystemBackend.
 class FileSystemBackendDelegate {
  public:
+  typedef base::Callback<void(const GURL&)> URLCallback;

[mtomasz, 2014/09/04 05:30:01]

This callback is same as in storage::FileSystemBackend. How about moving it
outside of the class to the storage namespace and reusing in other places?
Especially than URLCallback sounds very generic. WDYT?

[hirono, 2014/09/04 06:10:59]

I agree. Done.

+
   virtual ~FileSystemBackendDelegate() {}
 
   // Called from FileSystemBackend::GetAsyncFileUtil().
   virtual storage::AsyncFileUtil* GetAsyncFileUtil(
       storage::FileSystemType type) = 0;
 
   // Called from FileSystemBackend::CreateFileStreamReader().
   virtual scoped_ptr<storage::FileStreamReader> CreateFileStreamReader(
       const storage::FileSystemURL& url,
       int64 offset,
       const base::Time& expected_modification_time,
       storage::FileSystemContext* context) = 0;
 
   // Called from FileSystemBackend::CreateFileStreamWriter().
   virtual scoped_ptr<storage::FileStreamWriter> CreateFileStreamWriter(
       const storage::FileSystemURL& url,
       int64 offset,
       storage::FileSystemContext* context) = 0;
 
   // Called from the FileSystemWatcherService class. The returned pointer must
   // stay valid until shutdown.
   virtual storage::WatcherManager* GetWatcherManager(
       const storage::FileSystemURL& url) = 0;
+
+  // Called from FileSystemBackend::GetURLForBrowserTab.
+  virtual void GetURLForBrowserTab(
+      const storage::FileSystemURL& url,
+      const URLCallback& callback) = 0;
 };
 
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_CHROMEOS_FILEAPI_FILE_SYSTEM_BACKEND_DELEGATE_H_