Instead of ArrayBuffer, pass blob with printerProvider.onPrintRequested

extensions/common/api/printer_provider.idl

 // Copyright 2014 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.
 
 // <p>The <code>chrome.printerProvider</code> API exposes events used by print
 // manager to query printers controlled by extensions, to query their
 // capabilities and to submit print jobs to these printers.
 // <p/>
 // <p>Available only on dev channel since Chrome 42.</p>
 namespace printerProvider {
@@ skipping 34 matching lines @@
 
     // Print ticket in
     // <a href="https://developers.google.com/cloud-print/docs/cdd#cjt">
     // CJT format</a>.
     object ticket;
 
     // The document content type. Supported formats are
     // <code>"application/pdf"</code> and <code>"image/pwg-raster"</code>.
     DOMString contentType;
 
-    // Buffer containing the document to print. Format must match |contentType|.
-    ArrayBuffer document;
+    // Blob containing the document data to print. Format must match
+    // |contentType|.
+    [instanceOf=Blob] object document;
   };
 
   callback PrintersCallback = void(PrinterInfo[] printerInfo);
 
   // |capabilities|: Device capabilities in
   // <a href="https://developers.google.com/cloud-print/docs/cdd#cdd">CDD
   // format</a>.
   callback CapabilitiesCallback = void(object capabilities);
 
   callback PrintCallback = void(PrintError result);
@@ skipping 15 matching lines @@
 
     // Event fired when print manager requests printing.
     // |printJob|: The printing request parameters.
     // |resultCallback|: Callback that should be called when the printing
     // request is completed.
     static void onPrintRequested(PrintJob printJob,
                                  PrintCallback resultCallback);
   };
 };