extensions: Cleanup class/struct fwd declarations

extensions/browser/api/printer_provider_internal/printer_provider_internal_api.h

 // Copyright 2015 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_API_PRINTER_PROVIDER_INTERNAL_PRINTER_PROVIDER_INTERNAL_API_H_
 #define EXTENSIONS_BROWSER_API_PRINTER_PROVIDER_INTERNAL_PRINTER_PROVIDER_INTERNAL_API_H_
 
 #include <string>
 
 #include "base/macros.h"
 #include "base/observer_list.h"
 #include "extensions/browser/api/printer_provider_internal/printer_provider_internal_api_observer.h"
 #include "extensions/browser/browser_context_keyed_api_factory.h"
 #include "extensions/browser/extension_function.h"
 #include "extensions/common/api/printer_provider_internal.h"
 
 namespace base {
 class DictionaryValue;
-class ListValue;
 class RefCountedMemory;
 }
 
 namespace content {
 class BlobHandle;
 class BrowserContext;
 }
 
 namespace extensions {
 class Extension;
@@ skipping 143 matching lines @@
  private:
   DECLARE_EXTENSION_FUNCTION("printerProviderInternal.reportUsbPrinterInfo",
                              PRINTERPROVIDERINTERNAL_REPORTUSBPRINTERINFO)
 
   DISALLOW_COPY_AND_ASSIGN(PrinterProviderInternalReportUsbPrinterInfoFunction);
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_BROWSER_API_PRINTER_PROVIDER_INTERNAL_PRINTER_PROVIDER_INTERNAL_API_H_