extensions: Cleanup class/struct fwd declarations

extensions/browser/updater/extension_downloader_delegate.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 EXTENSIONS_BROWSER_UPDATER_EXTENSION_DOWNLOADER_DELEGATE_H_
 #define EXTENSIONS_BROWSER_UPDATER_EXTENSION_DOWNLOADER_DELEGATE_H_
 
 #include <set>
 #include <string>
 
 #include "base/callback.h"
 #include "base/time/time.h"
 #include "extensions/browser/crx_file_info.h"
 #include "extensions/browser/updater/manifest_fetch_data.h"
 
 class GURL;
 
-namespace base {
-class FilePath;
-}
-
 namespace extensions {
 
 class ExtensionDownloaderDelegate {
  public:
   virtual ~ExtensionDownloaderDelegate();
 
   // Passed as an argument to ExtensionDownloader::OnExtensionDownloadFailed()
   // to detail the reason for the failure.
   enum Error {
     // Background networking is disabled.
@@ skipping 93 matching lines @@
 
   // Invoked to get the current version of extension |id|. Returns false if
   // that extension is not installed.
   virtual bool GetExtensionExistingVersion(const std::string& id,
                                            std::string* version) = 0;
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_BROWSER_UPDATER_EXTENSION_DOWNLOADER_DELEGATE_H_