Added flags for PrintBrowser mode

printing/features/BUILD.gn

 # Copyright 2016 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//build/buildflag_header.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 any printing targets.
 
 buildflag_header("features") {
   header = "features.h"
 
+  # enable_print_browser requires enable_print_preview
+  if (enable_print_browser) {
+    enable_print_preview = true

[skau, 2016/12/16 18:05:53]

instead of forcing print_preview to be true, can you require that it's true and
throw an error otherwise.  This behavior seems surprising.

+  }
+
   # 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=$enable_print_preview",
+    "ENABLE_PRINT_BROWSER=$enable_print_browser",
   ]
 }