Allow top-level frames to request any USB device.

chrome/browser/ui/webui/print_preview/extension_printer_handler_unittest.cc

Index: chrome/browser/ui/webui/print_preview/extension_printer_handler_unittest.cc
diff --git a/chrome/browser/ui/webui/print_preview/extension_printer_handler_unittest.cc b/chrome/browser/ui/webui/print_preview/extension_printer_handler_unittest.cc
index 57715fa45da5b7cdd955ddc2ea1b6c6ed3a0bd42..64a80c506e79f7b3be79973736ecd87fce4831e9 100644
--- a/chrome/browser/ui/webui/print_preview/extension_printer_handler_unittest.cc
+++ b/chrome/browser/ui/webui/print_preview/extension_printer_handler_unittest.cc
@@ -566,6 +566,8 @@ TEST_F(ExtensionPrinterHandlerTest, GetUsbPrinters) {
   extension_printer_handler_->StartGetPrinters(
       base::Bind(&RecordPrinterList, &call_count, &printers, &is_done));
 
+  base::RunLoop().RunUntilIdle();
+
   FakePrinterProviderAPI* fake_api = GetPrinterProviderAPI();
   ASSERT_TRUE(fake_api);
   ASSERT_EQ(1u, fake_api->pending_get_printers_count());