[Extensions] Make chrome://extensions use developerPrivate for packing crxs

chrome/browser/extensions/api/developer_private/entry_picker.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 CHROME_BROWSER_EXTENSIONS_API_DEVELOPER_PRIVATE_ENTRY_PICKER_H_
 #define CHROME_BROWSER_EXTENSIONS_API_DEVELOPER_PRIVATE_ENTRY_PICKER_H_
 
 #include "extensions/browser/extension_function.h"
 #include "ui/shell_dialogs/select_file_dialog.h"
 
@@ skipping 24 matching lines @@
 
   // Allow picker UI to be skipped in testing.
   static void SkipPickerAndAlwaysSelectPathForTest(base::FilePath* path);
   static void SkipPickerAndAlwaysCancelForTest();
   static void StopSkippingPickerForTest();
 
  protected:
   ~EntryPicker() override;
 
  private:
-  // ui::SelectFileDialog::Listener implementation.
+  // ui::SelectFileDialog::Listener:
   void FileSelected(const base::FilePath& path,
                     int index,
                     void* params) override;
-
   void FileSelectionCanceled(void* params) override;
+  void MultiFilesSelected(const std::vector<base::FilePath>& files,
+                          void* params) override;
 
   scoped_refptr<ui::SelectFileDialog> select_file_dialog_;
   EntryPickerClient* client_;
 
   DISALLOW_COPY_AND_ASSIGN(EntryPicker);
 };
 
 }  // namespace api
 
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_API_DEVELOPER_PRIVATE_ENTRY_PICKER_H_