Change defaults for build args to accommodate Flutter and Fuchsia.

build/config/BUILDCONFIG.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.
 
 # =============================================================================
 # PLATFORM SELECTION
 # =============================================================================
 #
 # There are two main things to set: "os" and "cpu". The "toolchain" is the name
 # of the GN thing that encodes combinations of these things.
@@ skipping 178 matching lines @@
   is_fuchsia = false
   is_fuchsia_host = false
   is_ios = false
   is_linux = true
   is_mac = false
   is_nacl = false
   is_posix = true
   is_win = false
 }
 
+is_flutter = false

[zra, 2017/08/04 22:40:41]

This is probably not the right place for this since Flutter isn't really an OS.
Instead, this should probably be a new GN argument under a new file, like
//build/flutter_args.gni (in case we need to add more Flutter-specific arguments
later.) Then you can import build/flutter_args.gni where you need is_flutter,
and not worry about saying (defined(is_flutter) && is_flutter) everywhere.

+
 # =============================================================================
 # BUILD OPTIONS
 # =============================================================================
 
 # These Sanitizers all imply using the Clang compiler. On Windows they either
 # don't work or work differently.
 if (!is_clang && (is_asan || is_lsan || is_tsan || is_msan)) {
   is_clang = true
 }
 
@@ skipping 258 matching lines @@
       sources = invoker.sources
     }
     if (defined(invoker.testonly)) {
       testonly = invoker.testonly
     }
     if (defined(invoker.visibility)) {
       visibility = invoker.visibility
     }
   }
 }