Convert a few components from scoped_ptr to std::unique_ptr

components/printing/renderer/print_web_view_helper_mac.mm

 // 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.
 
 #include "components/printing/renderer/print_web_view_helper.h"
 
 #import <AppKit/AppKit.h>
 
 #include "base/logging.h"
 #include "base/mac/scoped_nsautorelease_pool.h"
@@ skipping 55 matching lines @@
   }
 
   Send(new PrintHostMsg_DidPrintPage(routing_id(), page_params));
 }
 
 #if defined(ENABLE_PRINT_PREVIEW)
 bool PrintWebViewHelper::RenderPreviewPage(
     int page_number,
     const PrintMsg_Print_Params& print_params) {
   PrintMsg_Print_Params printParams = print_params;
-  scoped_ptr<PdfMetafileSkia> draft_metafile;
+  std::unique_ptr<PdfMetafileSkia> draft_metafile;
   PdfMetafileSkia* initial_render_metafile = print_preview_context_.metafile();
 
   bool render_to_draft = print_preview_context_.IsModifiable() &&
                          is_print_ready_metafile_sent_;
 
   if (render_to_draft) {
     draft_metafile.reset(new PdfMetafileSkia());
     CHECK(draft_metafile->Init());
     initial_render_metafile = draft_metafile.get();
   }
@@ skipping 62 matching lines @@
 #endif  // defined(ENABLE_PRINT_PREVIEW)
     RenderPageContent(frame, page_number, canvas_area, content_area,
                       scale_factor, static_cast<blink::WebCanvas*>(canvas));
   }
 
   // Done printing. Close the device context to retrieve the compiled metafile.
   metafile->FinishPage();
 }
 
 }  // namespace printing