Cleanup remaining class/struct fwd declarations

printing/printing_context_linux.h

 // Copyright 2014 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 PRINTING_PRINTING_CONTEXT_LINUX_H_
 #define PRINTING_PRINTING_CONTEXT_LINUX_H_
 
 #include <string>
 
 #include "base/macros.h"
 #include "printing/printing_context.h"
 
-namespace base {
-class DictionaryValue;
-}
-
 namespace printing {
 
 class MetafilePlayer;
 class PrintDialogGtkInterface;
 
 // PrintingContext with optional native UI for print dialog and pdf_paper_size.
 class PRINTING_EXPORT PrintingContextLinux : public PrintingContext {
  public:
   explicit PrintingContextLinux(Delegate* delegate);
   ~PrintingContextLinux() override;
@@ skipping 34 matching lines @@
  private:
   base::string16 document_name_;
   PrintDialogGtkInterface* print_dialog_;
 
   DISALLOW_COPY_AND_ASSIGN(PrintingContextLinux);
 };
 
 }  // namespace printing
 
 #endif  // PRINTING_PRINTING_CONTEXT_LINUX_H_