Enable gold threaded link

build/config/compiler/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/config/android/config.gni")
 import("//build/config/chrome_build.gni")
 import("//build/config/compiler/compiler.gni")
 import("//build/config/nacl/config.gni")
 import("//build/toolchain/cc_wrapper.gni")
 import("//build/toolchain/toolchain.gni")
@@ skipping 190 matching lines @@
 
       # The x86 toolchain currently has problems with stack-protector.
       if (is_android && current_cpu == "x86") {
         cflags += [ "-fno-stack-protector" ]
       } else {
         cflags += [ "-fstack-protector" ]
       }
     }
 
     # Linker warnings.
-    if ( fatal_linker_warnings &&
-        !(is_chromeos && current_cpu == "arm") &&
+    if (fatal_linker_warnings && !(is_chromeos && current_cpu == "arm") &&
         !(is_android && use_order_profiling) && !is_mac && !is_ios) {
       # TODO(jochen): Enable this on chromeos on arm. http://crbug.com/356580
       # TODO(lizeb,pasko): Fix link errors when linking with order_profiling=1
       # crbug.com/485542
       ldflags += [ "-Wl,--fatal-warnings" ]
     }
   }
 
   if (is_clang && is_debug) {
     # Allow comparing the address of references and 'this' against 0
@@ skipping 90 matching lines @@
       }
 
       # Use -mstackrealign due to a bug on ia32 Jelly Bean.
       # See crbug.com/521527
       if (current_cpu == "x86") {
         cflags += [ "-mstackrealign" ]
       }
     } else {
       ldflags += [
         "-B$gold_path",
+
         # Experimentation found that using four linking threads
         # saved ~20% of link time.
         # https://groups.google.com/a/chromium.org/group/chromium-dev/browse_thread/thread/281527606915bb36
         # Only apply this to the target linker, since the host
         # linker might not be gold, but isn't used much anyway.
-        # TODO(raymes): Disable threading because gold is frequently
-        # crashing on the bots: crbug.com/161942.
-        #"-Wl,--threads",
-        #"-Wl,--thread-count=4",
+        "-Wl,--threads",
+        "-Wl,--thread-count=4",

[Nico, 2016/07/04 21:24:58]

I think we only want to enable this if we're using bundled gold (ie usually not
for builds with the cros tool chain). Is this checked for all already?

[tzik, 2016/07/05 04:05:58]

I think it wasn't. Added a condition to check linux_use_bundled_binutils here.

       ]
     }
 
     if (gdb_index) {
       ldflags += [ "-Wl,--gdb-index" ]
     }
 
     # TODO(thestig): Make this flag work with GN.
     #if (!is_official_build && !is_chromeos && !(is_asan || is_lsan || is_tsan || is_msan)) {
     #  ldflags += [
@@ skipping 1224 matching lines @@
 
 if (is_ios || is_mac) {
   # On Mac and iOS, this enables support for ARC (automatic ref-counting).
   # See http://clang.llvm.org/docs/AutomaticReferenceCounting.html.
   config("enable_arc") {
     common_flags = [ "-fobjc-arc" ]
     cflags_objc = common_flags
     cflags_objcc = common_flags
   }
 }