Print Preview: Change print to cr.sendWithPromise

chrome/test/data/webui/print_preview/print_preview_tests.js

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 cr.define('print_preview_test', function() {
   /**
    * Index of the "Save as PDF" printer.
    * @type {number}
    * @const
    */
@@ skipping 1289 matching lines @@
         return nativeLayer.whenCalled('getPrinterCapabilities', 'BarDevice')
             .then(function() {
               // Dispatch event indicating new preview has loaded.
               var previewDoneEvent = new Event(
                   print_preview.PreviewArea.EventType.PREVIEW_GENERATION_DONE);
               previewArea.dispatchEvent(previewDoneEvent);
 
               // Has active print button and successfully 'prints', indicating
               // recovery from error state.
               expectFalse(printButton.disabled);
-              expectFalse(nativeLayer.isPrintStarted());
               printButton.click();
-              expectTrue(nativeLayer.isPrintStarted());
+              // This should result in a call to print.
+              return nativeLayer.whenCalled('print');

[dpapad, 2017/06/23 00:13:57]

Related to comment in native_layer_stub.js, here we could be asserting that
nativeLayer.print() was called correctly.

             });
       });
     });
 
     // Test the preview generator to make sure the generate draft parameter is
     // set correctly. It should be false if the only change is the page range.
     test('GenerateDraft', function() {
       // Use a real preview generator.
       previewArea.previewGenerator_ =
           new print_preview.PreviewGenerator(printPreview.destinationStore_,
               printPreview.printTicketStore_, nativeLayer,
               printPreview.documentInfo_);
       return setupSettingsAndDestinationsWithCapabilities().then(function() {
         // The first request should generate draft because there was no
         // previous print preview draft.
         expectTrue(nativeLayer.generateDraft());
 
         // Change the page range - no new draft needed.
         printPreview.printTicketStore_.pageRange.updateValue('2');
         expectFalse(nativeLayer.generateDraft());
 
         // Change the margin type - need to regenerate again.
         printPreview.printTicketStore_.marginsType.updateValue(
             print_preview.ticket_items.MarginsTypeValue.NO_MARGINS);
         expectTrue(nativeLayer.generateDraft());
       });
     });
   });
 });