Add PrintedPage::GetCenteredPageContentRect so Mac and Win can share code.

printing/printed_page.cc

 // Copyright (c) 2006-2008 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 "printing/printed_page.h"
 
 namespace printing {
 
 PrintedPage::PrintedPage(int page_number,
                          NativeMetafile* native_metafile,
                          const gfx::Size& page_size,
                          const gfx::Rect& page_content_rect,
                          bool has_visible_overlays)
     : page_number_(page_number),
       native_metafile_(native_metafile),
       page_size_(page_size),
       page_content_rect_(page_content_rect),
       has_visible_overlays_(has_visible_overlays) {
 }
 
 PrintedPage::~PrintedPage() {
 }
 
 const NativeMetafile* PrintedPage::native_metafile() const {
   return native_metafile_.get();
 }
 
+void PrintedPage::GetCenteredPageContentRect(
+    const gfx::Size& paper_size, gfx::Rect* content_rect) const {
+  *content_rect = page_content_rect();
+  if (paper_size.width() > page_size().width()) {
+    int diff = paper_size.width() - page_size().width();
+    content_rect->set_x(content_rect->x() + diff / 2);
+  }
+  if (paper_size.height() > page_size().height()) {
+    int diff = paper_size.height() - page_size().height();
+    content_rect->set_y(content_rect->y() + diff / 2);
+  }
+}
+
 }  // namespace printing