Guarded shrink setting with ifdefs to make clear where it is used.

printing/printed_page.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_PRINTED_PAGE_H_
 #define PRINTING_PRINTED_PAGE_H_
 
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
 #include "printing/metafile.h"
 #include "ui/gfx/rect.h"
 #include "ui/gfx/size.h"
 
 namespace printing {
 
 // Contains the data to reproduce a printed page, either on screen or on
 // paper. Once created, this object is immutable. It has no reference to the
 // PrintedDocument containing this page.
 // Note: May be accessed from many threads at the same time. This is an non
 // issue since this object is immutable. The reason is that a page may be
 // printed and be displayed at the same time.
 class PRINTING_EXPORT PrintedPage
     : public base::RefCountedThreadSafe<PrintedPage> {
  public:
   PrintedPage(int page_number,
               Metafile* metafile,
               const gfx::Size& page_size,
-              const gfx::Rect& page_content_rect,
-              double shrink_factor);
+              const gfx::Rect& page_content_rect);
 
   // Getters
   int page_number() const { return page_number_; }
   const Metafile* metafile() const;
   const gfx::Size& page_size() const { return page_size_; }
   const gfx::Rect& page_content_rect() const { return page_content_rect_; }
+#if defined(OS_WIN)
+  void set_shrink_factor(double shrink_factor) {
+    shrink_factor_ = shrink_factor;
+  }
   double shrink_factor() const { return shrink_factor_; }
+#endif  // OS_WIN
 
   // Get page content rect adjusted based on
   // http://dev.w3.org/csswg/css3-page/#positioning-page-box
   void GetCenteredPageContentRect(const gfx::Size& paper_size,
                                   gfx::Rect* content_rect) const;
 
  private:
   friend class base::RefCountedThreadSafe<PrintedPage>;
 
   ~PrintedPage();
 
   // Page number inside the printed document.
   const int page_number_;
 
   // Actual paint data.
   const scoped_ptr<Metafile> metafile_;
 
+#if defined(OS_WIN)
+  // Shrink done in comparison to desired_dpi.
+  double shrink_factor_;
+#endif  // OS_WIN
+
   // The physical page size. To support multiple page formats inside on print
   // job.
   const gfx::Size page_size_;
 
   // The printable area of the page.
   const gfx::Rect page_content_rect_;
 
-  // Shrink done in comparison to desired_dpi.
-  double shrink_factor_;
-
   DISALLOW_COPY_AND_ASSIGN(PrintedPage);
 };
 
 }  // namespace printing
 
 #endif  // PRINTING_PRINTED_PAGE_H_