Add GetURLForBrowserTab method to the external file system backend.

webkit/browser/fileapi/file_system_backend.h

 // Copyright (c) 2012 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_BROWSER_FILEAPI_FILE_SYSTEM_BACKEND_H_
 #define WEBKIT_BROWSER_FILEAPI_FILE_SYSTEM_BACKEND_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 29 matching lines @@
 // NOTE: when you implement a new FileSystemBackend for your own
 // FileSystem module, please contact to kinuko@chromium.org.
 //
 class STORAGE_EXPORT FileSystemBackend {
  public:
   // Callback for InitializeFileSystem.
   typedef base::Callback<void(const GURL& root_url,
                               const std::string& name,
                               base::File::Error error)>
       OpenFileSystemCallback;
+  typedef base::Callback<void(const GURL& url)> URLCallback;
   virtual ~FileSystemBackend() {}
 
   // Returns true if this filesystem backend can handle |type|.
   // One filesystem backend may be able to handle multiple filesystem types.
   virtual bool CanHandleType(FileSystemType type) const = 0;
 
   // This method is called right after the backend is registered in the
   // FileSystemContext and before any other methods are called. Each backend can
   // do additional initialization which depends on FileSystemContext here.
   virtual void Initialize(FileSystemContext* context) = 0;
@@ skipping 90 matching lines @@
   virtual void GrantFileAccessToExtension(
       const std::string& extension_id,
       const base::FilePath& virtual_path) = 0;
   // Revokes file access from extension identified with |extension_id|.
   virtual void RevokeAccessForExtension(
         const std::string& extension_id) = 0;
   // Gets virtual path by known filesystem path. Returns false when filesystem
   // path is not exposed by this provider.
   virtual bool GetVirtualPath(const base::FilePath& file_system_path,
                               base::FilePath* virtual_path) = 0;
+  // Gets an redirect URL for browser tab. e.g. Google Drive URL for hosted
+  // documents. Returns empty URL if the entry does not have the redirect URL.
+  virtual void GetURLForBrowserTab(
+      const storage::FileSystemURL& url,
+      const URLCallback& callback) = 0;
 };
 
 }  // namespace storage
 
 #endif  // WEBKIT_BROWSER_FILEAPI_FILE_SYSTEM_BACKEND_H_