Add feature flag for Windows printing with XPS

Windows printing path is being modernized from using the pre-WinXP GDI
print API to an XPS-based API.  Changes to support this new print path
will be guarded behind a feature flag that defaults to off for now.

Bug: 1008222
Change-Id: I5111f155cd44910fb7fa09cff32cf50b3b4e3c58
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1925760
Commit-Queue: Alan Screen <[email protected]>
Reviewed-by: Lei Zhang <[email protected]>
Cr-Commit-Position: refs/heads/master@{#717852}
diff --git a/chrome/browser/about_flags.cc b/chrome/browser/about_flags.cc
index d196fdd7..14f4f3f 100644
--- a/chrome/browser/about_flags.cc
+++ b/chrome/browser/about_flags.cc
@@ -3297,7 +3297,13 @@
     {"harfbuzz-pdf-subsetter", flag_descriptions::kHarfBuzzPDFSubsetterName,
      flag_descriptions::kHarfBuzzPDFSubsetterDescription, kOsAll,
      FEATURE_VALUE_TYPE(printing::features::kHarfBuzzPDFSubsetter)},
-#endif
+
+#if defined(OS_WIN)
+    {"use-xps-for-printing", flag_descriptions::kUseXpsForPrintingName,
+     flag_descriptions::kUseXpsForPrintingDescription, kOsWin,
+     FEATURE_VALUE_TYPE(printing::features::kUseXpsForPrinting)},
+#endif // defined(OS_WIN)
+#endif // BUILDFLAG(ENABLE_PRINTING)
 
     {"autofill-profile-client-validation",
      flag_descriptions::kAutofillProfileClientValidationName,