Use unique_ptrs in PrintPreviewDataService.

chrome/browser/printing/print_preview_data_service.h

Index: chrome/browser/printing/print_preview_data_service.h
diff --git a/chrome/browser/printing/print_preview_data_service.h b/chrome/browser/printing/print_preview_data_service.h
index 9052528216337c9e5fae8d80b53456256002db59..5fa52e30b8f60701be8a41e13bf390c83b2995d0 100644
--- a/chrome/browser/printing/print_preview_data_service.h
+++ b/chrome/browser/printing/print_preview_data_service.h
@@ -8,6 +8,7 @@
 #include <stdint.h>
 
 #include <map>
+#include <memory>
 #include <string>
 
 #include "base/macros.h"
@@ -57,7 +58,7 @@ class PrintPreviewDataService {
   // Key: PrintPreviewUI ID.
   // Value: Print preview data store object.
   using PreviewDataStoreMap =
-      std::map<int32_t, scoped_refptr<PrintPreviewDataStore>>;
+      std::map<int32_t, std::unique_ptr<PrintPreviewDataStore>>;
 
   PrintPreviewDataService();
   ~PrintPreviewDataService();