Convert enable_bidirectional_stream into build flag local to net.

net/BUILD.gn

 # Copyright (c) 2013 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("//build/config/chromecast_build.gni")
 import("//build/config/compiler/compiler.gni")
 import("//build/config/crypto.gni")
 import("//build/config/features.gni")
 import("//build/config/ui.gni")
 import("//build_overrides/v8.gni")
 import("//testing/test.gni")
 import("//third_party/icu/config.gni")
 import("//third_party/protobuf/proto_library.gni")
 import("//tools/grit/grit_rule.gni")
@@ skipping 21 matching lines @@
 # android devices, but we cannot be so sure about the variety of ARM devices.
 # So enable it for x86 only for now.
 posix_avoid_mmap = is_android && current_cpu != "x86"
 
 use_v8_in_net = !is_ios
 enable_built_in_dns = !is_ios
 
 declare_args() {
   # Disables support for file URLs.  File URL support requires use of icu.
   disable_file_support = false
+
+  # Enables BidirectionalStream; Used in cronet, disabled by default.
   enable_bidirectional_stream = false
 
   # WebSockets and socket stream code are not used on iOS and are optional in
   # cronet.
   enable_websockets = !is_ios
   disable_ftp_support = is_ios
 }
 
 config("net_config") {
   defines = []
   if (posix_avoid_mmap) {
     defines += [ "POSIX_AVOID_MMAP" ]
   }
   if (disable_file_support) {
     defines += [ "DISABLE_FILE_SUPPORT" ]
   }
   if (disable_ftp_support) {
     defines += [ "DISABLE_FTP_SUPPORT=1" ]
   }
-  if (enable_bidirectional_stream) {
-    defines += [ "ENABLE_BIDIRECTIONAL_STREAM=1" ]
-  }
 }
 
 # net_internal_config is shared with net and net_small.
 config("net_internal_config") {
   defines = [
     # TODO(GYP) Note that the GYP file supports linux_link_kerberos (defaults to
     # 0) which implies that we run pkg_config on kerberos and link to that
     # rather than setting this define which will dynamically open it. That
     # doesn't seem to be set in the regular builds, so we're skipping this
     # capability here.
@@ skipping 20 matching lines @@
 
 net_shared_configs = [
   ":net_internal_config",
   "//build/config:precompiled_headers",
 
   # TODO(jschuh): crbug.com/167187 fix size_t to int truncations.
   "//build/config/compiler:no_size_t_to_int_warning",
 ]
 
 net_shared_public_deps = [
+  ":features",
   ":net_quic_proto",
   "//crypto",
   "//crypto:platform",
 ]
 
 net_shared_deps = [
   ":net_resources",
   "//base",
   "//net/base/registry_controlled_domains",
   "//third_party/protobuf:protobuf_lite",
@@ skipping 1592 matching lines @@
   if (enable_websockets) {
     sources += [ "websockets/websocket_frame_perftest.cc" ]
   }
 
   if (use_v8_in_net) {
     deps += [ ":net_with_v8" ]
   } else {
     sources -= [ "proxy/proxy_resolver_perftest.cc" ]
   }
 }
+
+buildflag_header("features") {
+  header = "net_features.h"
+
+  flags = [ "ENABLE_BIDIRECTIONAL_STREAM=$enable_bidirectional_stream" ]
+}