printer.AddGenericPrinter is failing consistently on release builders. For example, from http://stainless/browse/chromeos-autotest-results/257536598-chromeos-test/ :

2018/11/15 09:11:22 Started test printer.AddGenericPrinter
2018/11/15 09:11:22 [09:11:21.880] Waiting for org.chromium.debugd D-Bus service
2018/11/15 09:11:22 [09:11:21.880] Registering a printer
2018/11/15 09:11:22 [09:11:22.048] Issuing print request
2018/11/15 09:11:22 [09:11:22.091] Receiving print request
2018/11/15 09:11:26 [09:11:26.122] Error at add_generic_printer.go:100: Read request has diff from the golden file, dumped at printer_add_generic_printer_diff.txt
2018/11/15 09:11:26 [09:11:26.122] Stack trace:
Read request has diff from the golden file, dumped at printer_add_generic_printer_diff.txt
	at chromiumos/tast/local/bundles/cros/printer.AddGenericPrinter (add_generic_printer.go:100)
	at chromiumos/tast/testing.(*Test).Run.func4 (test.go:189)
	at chromiumos/tast/testing.runStages.func1.1 (stage.go:39)
	at chromiumos/tast/testing.runAndRecover.func1 (stage.go:69)
	at runtime.goexit (asm_amd64.s:2361)
2018/11/15 09:11:27 Completed test printer.AddGenericPrinter in 4.784s with 1 error(s)

Here's the diff:

@@ -4,8 +4,8 @@
 %%LanguageLevel: 3
 %%DocumentSuppliedResources: (atend)
 %%DocumentMedia: Letter 612 792 0 () ()
-%%For: (anonymous)
-%%Title: (Untitled)
+%%For: (root)
+%%Title: (to_print.pdf)
 %RBINumCopies: 1
 %%Pages: (atend)
 %%BoundingBox: (atend)