Interrogate PpdProvider from PrintPreview.

chrome/browser/ui/webui/print_preview/print_preview_handler.h

Index: chrome/browser/ui/webui/print_preview/print_preview_handler.h
diff --git a/chrome/browser/ui/webui/print_preview/print_preview_handler.h b/chrome/browser/ui/webui/print_preview/print_preview_handler.h
index 42a8f52ce91d862e6cb77fa45ff6636412f7eea0..56a737952dbf7504e6114e8e2d6f6068d083e812 100644
--- a/chrome/browser/ui/webui/print_preview/print_preview_handler.h
+++ b/chrome/browser/ui/webui/print_preview/print_preview_handler.h
@@ -41,6 +41,10 @@ namespace gfx {
 class Size;
 }
 
+namespace printing {
+class PrinterBackendProxy;
+}
+
 // The handler for Javascript messages related to the print preview dialog.
 class PrintPreviewHandler
     : public content::WebUIMessageHandler,
@@ -111,6 +115,8 @@ class PrintPreviewHandler
 
   PrintPreviewUI* print_preview_ui() const;
 
+  printing::PrinterBackendProxy* printer_backend_proxy();
+
   // Gets the list of printers. |args| is unused.
   void HandleGetPrinters(const base::ListValue* args);
 
@@ -380,6 +386,10 @@ class PrintPreviewHandler
   // notify the test if it was a successful save, only that it was attempted.
   base::Closure pdf_file_saved_closure_;
 
+  // Proxy for calls to the print backend.  Lazily initialized since web_ui() is
+  // not available at construction time.
+  std::unique_ptr<printing::PrinterBackendProxy> printer_backend_proxy_;
+
   base::WeakPtrFactory<PrintPreviewHandler> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(PrintPreviewHandler);