Move printing defines to buildflag system.

printing/features/BUILD.gn

Index: printing/features/BUILD.gn
diff --git a/ppapi/features/BUILD.gn b/printing/features/BUILD.gn
similarity index 52%
copy from ppapi/features/BUILD.gn
copy to printing/features/BUILD.gn
index 3917d1ee992a9d5ab7686d9a99d23e67de9b26b2..cdcfd794774c97648b2ce43f6eae4ec841b18d23 100644
--- a/ppapi/features/BUILD.gn
+++ b/printing/features/BUILD.gn
@@ -3,13 +3,21 @@
 # found in the LICENSE file.
 
 import("//build/buildflag_header.gni")
-import("//ppapi/features/features.gni")
+import("//printing/features/features.gni")
 
 # This file is in a separate directory so all targets in the build can refer to
 # the buildflag header to get the necessary preprocessor defines without
-# bringing in all of Pepper.
+# bringing in any printing targets.
 
 buildflag_header("features") {
   header = "features.h"
-  flags = [ "ENABLE_PEPPER_CDMS=$enable_pepper_cdms" ]
+
+  # Convenience define for ENABLE_BASIC_PRINTING || ENABLE_PRINT_PREVIEW.
+  enable_printing = enable_basic_printing || enable_print_preview
+
+  flags = [
+    "ENABLE_PRINTING=$enable_printing",
+    "ENABLE_BASIC_PRINTING=$enable_basic_printing",
+    "ENABLE_PRINT_PREVIEW=$enable_print_preview",
+  ]
 }