Print Preview: change getPreview to cr.sendWithPromise

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 3fc478f6df48099b254b681173b765a7a2be6c43..34725e3ab04c4df43c1687b63a2bc422dd10ec5f 100644
--- a/chrome/browser/ui/webui/print_preview/print_preview_handler.h
+++ b/chrome/browser/ui/webui/print_preview/print_preview_handler.h
@@ -6,6 +6,7 @@
 #define CHROME_BROWSER_UI_WEBUI_PRINT_PREVIEW_PRINT_PREVIEW_HANDLER_H_
 
 #include <memory>
+#include <queue>
 #include <string>
 
 #include "base/files/file_path.h"
@@ -76,6 +77,15 @@ class PrintPreviewHandler
   // Called when print preview failed.
   void OnPrintPreviewFailed();
 
+  // Called when print preview is cancelled due to a new request.
+  void OnPrintPreviewCancelled();
+
+  // Called when printer settings were invalid.
+  void OnInvalidPrinterSettings();
+
+  // Called when print preview is ready.
+  void OnPrintPreviewReady(int preview_uid, int request_id);
+
 #if BUILDFLAG(ENABLE_BASIC_PRINTING)
   // Called when the user press ctrl+shift+p to display the native system
   // dialog.
@@ -421,6 +431,8 @@ class PrintPreviewHandler
   // notify the test if it was a successful save, only that it was attempted.
   base::Closure pdf_file_saved_closure_;
 
+  std::queue<std::string> preview_callbacks_;
+
 #if BUILDFLAG(ENABLE_SERVICE_DISCOVERY)
   // Callback ID to be used to notify UI that privet search is finished.
   std::string privet_search_callback_id_;