Instead of ArrayBuffer, pass blob with printerProvider.onPrintRequested

extensions/test/data/api_test/printer_provider/request_print/test.js

Index: extensions/test/data/api_test/printer_provider/request_print/test.js
diff --git a/extensions/test/data/api_test/printer_provider/request_print/test.js b/extensions/test/data/api_test/printer_provider/request_print/test.js
index 868898dd1fdcf8251d7578cd7b398daca0ccd937..80491ddbcceb1573590a231fc935506bb8655f8c 100644
--- a/extensions/test/data/api_test/printer_provider/request_print/test.js
+++ b/extensions/test/data/api_test/printer_provider/request_print/test.js
@@ -2,6 +2,15 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+function readBlob(blob, callback) {
+  var reader = new FileReader();
+  reader.onerror = function() { callback(null); };
+  reader.onloadend = function() {
+    callback(reader.result);
+  }
+  reader.readAsText(blob)
+}
+
 chrome.test.sendMessage('loaded', function(test) {
   chrome.test.runTests([function printTest() {
     if (test == 'NO_LISTENER') {
@@ -33,18 +42,31 @@ chrome.test.sendMessage('loaded', function(test) {
             'Invalid value for argument 1. ' +
             'Value must be one of: ' +
             '[OK, FAILED, INVALID_TICKET, INVALID_DATA].');
+         chrome.test.succeed();
+      } else if (test == 'OK') {

[not at google - send to devlin, 2015/03/04 21:54:50]

Looks odd that the rest of the test uses the pattern

if (test == whatever) {
  something();
  succeed();
  return;
}
if (test == anotherthing) {
  ...
}

but here you're doing

if (test == whatever) {
  something();
  succeed();
} else if (test == anotherthing) {
  ..
}

I think the whole test should use if-else, or better, switch - up to you. Either
way consistent.

[tbarzic, 2015/03/04 23:24:34]

Done.

+        readBlob(job.document, function(content) {
+          callback(!!content ? 'OK' : 'INVALID_DATA');
+
+          if (content)
+            chrome.test.assertEq('bytes', content);
+
+          chrome.test.assertThrows(
+              callback,
+              [test],
+              'Event callback must not be called more than once.');
+          chrome.test.succeed();
+        });
       } else {
-        chrome.test.assertTrue(test == 'OK' || test == 'FAILED' ||
-            test == 'INVALID_TICKET' || test == 'INVALID_DATA');
+        chrome.test.assertTrue(test == 'FAILED' || test == 'INVALID_TICKET' ||
+                               test == 'INVALID_DATA');

[not at google - send to devlin, 2015/03/04 21:54:50]

If you used a switch you could make this look a bit nicer as well:

case 'FAILED':
case 'INVALID_TICKET':
case 'INVALID_DATA':
  ...
  break;
default:
  chrome.test.fail('Invalid input');

[tbarzic, 2015/03/04 23:24:34]

Done.

         callback(test);
+        chrome.test.assertThrows(
+            callback,
+            [test],
+            'Event callback must not be called more than once.');
+        chrome.test.succeed();
       }
 
-      chrome.test.assertThrows(
-          callback,
-          [test],
-          'Event callback must not be called more than once.');
-
-      chrome.test.succeed();
     });
 
     chrome.test.sendMessage('ready');