Switch Chrome on Linux to libc++

build/config/c++/c++.gni

 # Copyright 2017 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/sanitizers/sanitizers.gni")
 
 if (current_toolchain != default_toolchain) {
   use_custom_libcxx = false
 }
 
 declare_args() {
   # Use libc++ (buildtools/third_party/libc++ and
   # buildtools/third_party/libc++abi) instead of stdlibc++ as standard
   # library.
   use_custom_libcxx =
+      (is_linux && !is_chromeos) ||

[Nico, 2017/06/29 18:30:54]

The next line suggests that this wants to be is_linux && !is_chromeos &&
(!is_chromecast || is_cast_desktop_build). You can also remove the next line
then.

I think you can almost remove the whole rest of the line – we only use tsan and
msan on linux. This is probably also true for ubsan, and we don't want to use
custom_libcxx on mac (at least atm) so we don't need the libfuzzer bit. But
maybe safer to not do that in this change.

[Tom Anderson, 2017/06/29 19:42:11]

Done.  I'll hold off on changing the second half so I added a TODO in the
meantime explaining what still needs to be cleaned up.

       (is_asan && is_linux && !is_chromeos &&
        (!is_chromecast || is_cast_desktop_build)) || is_tsan || is_msan ||
       is_ubsan || is_ubsan_security || (use_libfuzzer && !is_mac) || use_afl
 }