Standardize "net" category trace events

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")
@@ skipping 68 matching lines @@
 ]
 
 if (use_glib && use_gconf && !is_chromeos) {
   net_configs += [ "//build/config/linux/gconf" ]
 }
 
 if (is_linux) {
   net_configs += [ "//build/config/linux:libresolv" ]
 }
 
+source_set("constants") {

[xunjieli, 2016/12/02 22:35:53]

Thanks so much for the ideas! I was able to reproduce this on my windows
machine. If I try to use net/base/net_errors.h in proxy_resolver_v8_tracing.cc,
I will get the same linker error.

I searched on chromium-dev, it seems that the way to solve this in GN is to have
a separate target either as a source_set or static_library for the
constants(e.g. common:constants, chrome_elf:constants,
remoting/host/mac:constants).

I have updated the CL. Please take a look at the diff between PS#4 and PS#5.

+  sources = [
+    "base/trace_constants.cc",
+    "base/trace_constants.h",
+  ]
+  deps = [
+    "//base",
+  ]
+}
+
 component("net") {
   sources = gypi_values.net_nacl_common_sources
   net_unfiltered_sources = []
 
   deps = [
+    ":constants",
     ":net_resources",
     "//base",
     "//net/base/registry_controlled_domains",
     "//third_party/protobuf:protobuf_lite",
     "//url:url_features",
   ]
 
   public_deps = [
     ":net_quic_proto",
     "//crypto",
@@ skipping 576 matching lines @@
 
     defines = [ "NET_IMPLEMENTATION" ]
 
     configs += [
       "//build/config/compiler:no_size_t_to_int_warning",
       "//build/config/compiler:wexit_time_destructors",
       "//v8:external_startup_data",
     ]
 
     public_deps = [
+      ":constants",
       ":net",
     ]
     deps = [
       "//base",
       "//gin",
       "//url",
       "//v8",
     ]
   }
 }
@@ skipping 1353 matching lines @@
     "http/http_security_headers_hpkp_report_only_fuzzer.cc",
   ]
   deps = [
     ":net_fuzzer_test_support",
     "//base",
     "//net",
     "//url",
   ]
   dict = "data/fuzzer_dictionaries/net_http_security_headers_fuzzer.dict"
 }