Get printing working in Aura.

printing/printed_document_cairo.cc

Index: printing/printed_document_cairo.cc
diff --git a/printing/printed_document_cairo.cc b/printing/printed_document_cairo.cc
index 15193c7f68727c8fdc0600c34ab247039e4d8f07..7a1fb3218598ee239126a701d04e889a4b8d1039 100644
--- a/printing/printed_document_cairo.cc
+++ b/printing/printed_document_cairo.cc
@@ -7,7 +7,7 @@
 #include "base/logging.h"
 #include "printing/page_number.h"
 #include "printing/printed_page.h"
-#include "printing/printing_context_cairo.h"
+#include "printing/printing_context_gtk.h"
 
 namespace printing {
 
@@ -27,7 +27,7 @@ void PrintedDocument::RenderPrintedPage(
   {
     base::AutoLock lock(lock_);
     if (page.page_number() - 1 == mutable_.first_page) {
-      reinterpret_cast<PrintingContextCairo*>(context)->PrintDocument(
+      reinterpret_cast<PrintingContextGtk*>(context)->PrintDocument(
           page.metafile());
     }
   }