Fix a bunch of IWYU violators that don't include scoped_ptr.h

printing/printing_context.h

 // Copyright (c) 2011 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_H_
 #define PRINTING_PRINTING_CONTEXT_H_
 
 #include <string>
 
 #include "base/callback.h"
 #include "base/macros.h"
+#include "base/memory/scoped_ptr.h"
 #include "base/strings/string16.h"
 #include "printing/print_settings.h"
 #include "ui/gfx/native_widget_types.h"
 
 namespace base {
 class DictionaryValue;
 }
 
 namespace printing {
 
@@ skipping 124 matching lines @@
   // Did the user cancel the print job.
   volatile bool abort_printing_;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(PrintingContext);
 };
 
 }  // namespace printing
 
 #endif  // PRINTING_PRINTING_CONTEXT_H_