Fix generation of the complete metafile for print preview flow.

chrome/renderer/print_web_view_helper_mac.mm

Index: chrome/renderer/print_web_view_helper_mac.mm
diff --git a/chrome/renderer/print_web_view_helper_mac.mm b/chrome/renderer/print_web_view_helper_mac.mm
index 55cccb650a20b756130bb4427995f21867fb4bbf..cd640ed28911c89ca8e499179822a5a54ea396de 100644
--- a/chrome/renderer/print_web_view_helper_mac.mm
+++ b/chrome/renderer/print_web_view_helper_mac.mm
@@ -68,7 +68,7 @@ void PrintWebViewHelper::RenderPreviewPage(int page_number) {
 
   printing::Metafile* initial_render_metafile =
       print_preview_context_.metafile();
-  scoped_ptr<printing::Metafile> draft_metafile;
+  scoped_ptr<printing::PreviewMetafile> draft_metafile;
 #if !defined(USE_SKIA)
   if (print_preview_context_.IsModifiable()) {
     draft_metafile.reset(new printing::PreviewMetafile);
@@ -96,15 +96,24 @@ void PrintWebViewHelper::RenderPreviewPage(int page_number) {
 
     // With CG, we rendered into a new metafile so we could get it as a draft
     // document.  Now we need to add it to complete document.
+    printing::Metafile* complete_metafile = print_preview_context_.metafile();
+    bool success = complete_metafile->StartPage(
+        printParams.page_size, gfx::Rect(printParams.page_size), 1.0);

[kmadhusu, 2011/08/05 23:33:52]

Please document that the scale factor is always 1.0.

[kmadhusu, 2011/08/05 23:33:52]

Why can't we use the content_area rather than
"gfx::Rect(printParams.page_size)"?

[vandebo (ex-Chrome), 2011/08/06 00:43:43]

Done.

[vandebo (ex-Chrome), 2011/08/06 00:43:43]

Because we want a 1:1 rendering of the source PDF, we need to draw into the
entire page (arg I've specified), not the content area (smaller).

+    DCHECK(success);
+    // StartPage unconditionally flips the content over, flip it back since it
+    // was already flipped in draft_metafile.
+    CGContextTranslateCTM(complete_metafile->context(), 0,
+                          printParams.page_size.height());
+    CGContextScaleCTM(complete_metafile->context(), 1.0, -1.0);
+
     draft_metafile->RenderPage(1,
-                               print_preview_context_.metafile()->context(),
-                               CGRectMake(content_area.x(), content_area.y(),
-                                          content_area.width(),
-                                          content_area.height()),
-                               false /*shrunk_to_fit*/,
+                               complete_metafile->context(),
+                               draft_metafile->GetPageBounds(1).ToCGRect(),
+                               false /*shrink_to_fit*/,

[kmadhusu, 2011/08/05 23:33:52]

style nit: Add a space after "/*" and before "*/".

[vandebo (ex-Chrome), 2011/08/06 00:43:43]

Done.

                                false /*stretch_to_fit*/,
                                true /*center_horizontally*/,
                                true /*center_vertically*/);
+    complete_metafile->FinishPage();
 #endif
   }