Fix printing crash

CHECK is failing because if the preview is a subset of the document and
is cancelled or fails after the subset is completed but while draft data
is still being generated, 2 messages are sent to the UI. Fix this issue
so that only 1 message is sent to the UI per preview request.

Bug: 740377
Change-Id: I751432f24e6283a55939a51cfe452f331da3f850
Reviewed-on: https://chromium-review.googlesource.com/571516
Commit-Queue: Rebekah Potter <rbpotter@chromium.org>
Reviewed-by: Lei Zhang <thestig@chromium.org>
Reviewed-by: Demetrios Papadopoulos <dpapad@chromium.org>
Cr-Commit-Position: refs/heads/master@{#487348}

components/printing/renderer/print_web_view_helper.cc

@@ -1572,12 +1572,14 @@ void PrintWebViewHelper::DidFinishPrinting(PrintingResult result) {
 
 #if BUILDFLAG(ENABLE_PRINT_PREVIEW)
     case FAIL_PREVIEW:
+      if (!is_print_ready_metafile_sent_) {
         if (notify_browser_of_print_failure_) {
           LOG(ERROR) << "CreatePreviewDocument failed";
           Send(new PrintHostMsg_PrintPreviewFailed(routing_id(), cookie));
         } else {
           Send(new PrintHostMsg_PrintPreviewCancelled(routing_id(), cookie));
         }
+      }
       print_preview_context_.Failed(notify_browser_of_print_failure_);
       break;
     case INVALID_SETTINGS: