extensions: Cleanup class/struct fwd declarations

extensions/browser/sandboxed_unpacker.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_SANDBOXED_UNPACKER_H_
 #define EXTENSIONS_BROWSER_SANDBOXED_UNPACKER_H_
 
 #include <string>
 
 #include "base/files/file_path.h"
@@ skipping 12 matching lines @@
 
 namespace base {
 class DictionaryValue;
 class SequencedTaskRunner;
 }
 
 namespace content {
 class UtilityProcessHost;
 }
 
-namespace crypto {
-class SecureHash;
-}
-
 namespace extensions {
 class Extension;
 
 class SandboxedUnpackerClient
     : public base::RefCountedDeleteOnMessageLoop<SandboxedUnpackerClient> {
  public:
   // Initialize the ref-counted base to always delete on the UI thread. Note
   // the constructor call must also happen on the UI thread.
   SandboxedUnpackerClient();
 
@@ skipping 261 matching lines @@
 
   // Used for sending tasks to the utility process.
   scoped_refptr<UtilityHostWrapper> utility_wrapper_;
 
   DISALLOW_COPY_AND_ASSIGN(SandboxedUnpacker);
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_BROWSER_SANDBOXED_UNPACKER_H_