Add Math.ceil to pageSize.height and pageSize.width to printToPDF() options to prevent error on display.

lib/browser/api/web-contents.js

@@ -198,8 +198,8 @@ WebContents.prototype.printToPDF = function (options, callback) {
       printingSetting.mediaSize = {
         name: 'CUSTOM',
         custom_display_name: 'Custom',
-        height_microns: pageSize.height,
-        width_microns: pageSize.width
+        height_microns: Math.ceil(pageSize.height),
+        width_microns: Math.ceil(pageSize.width)
       }
     } else if (PDFPageSizes[pageSize]) {
       printingSetting.mediaSize = PDFPageSizes[pageSize]