Add support for starting an extension print job to print preview

chrome/browser/resources/print_preview/print_preview.js

 // Copyright (c) 2012 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.
 
 // TODO(rltoscano): Move data/* into print_preview.data namespace
 
 <include src="component.js">
 <include src="print_preview_focus_manager.js">
 
 cr.define('print_preview', function() {
@@ skipping 511 matching lines @@
         this.uiState_ = PrintPreview.UiState_.PRINTING;
       }
       this.setIsEnabled_(false);
       this.printHeader_.isCancelButtonEnabled = true;
       var printAttemptResult = this.printIfReady_();
       if (printAttemptResult == PrintPreview.PrintAttemptResult_.PRINTED ||
           printAttemptResult ==
               PrintPreview.PrintAttemptResult_.READY_WAITING_FOR_PREVIEW) {
         if ((this.destinationStore_.selectedDestination.isLocal &&
              !this.destinationStore_.selectedDestination.isPrivet &&
+             !this.destinationStore_.selectedDestination.isExtension &&
              this.destinationStore_.selectedDestination.id !=
                  print_preview.Destination.GooglePromotedId.SAVE_AS_PDF) ||
              this.uiState_ == PrintPreview.UiState_.OPENING_PDF_PREVIEW) {
           // Hide the dialog for now. The actual print command will be issued
           // when the preview generation is done.
           this.nativeLayer_.startHideDialog();
         }
       }
     },
 
@@ skipping 766 matching lines @@
 <include src="search/cloud_destination_list.js">
 <include src="search/recent_destination_list.js">
 <include src="search/destination_list_item.js">
 <include src="search/destination_search.js">
 <include src="search/fedex_tos.js">
 
 window.addEventListener('DOMContentLoaded', function() {
   printPreview = new print_preview.PrintPreview();
   printPreview.initialize();
 });