Land prep work to enable NaCl in the Linux x64 GN builds.

build/config/BUILDCONFIG.gn

Index: build/config/BUILDCONFIG.gn
diff --git a/build/config/BUILDCONFIG.gn b/build/config/BUILDCONFIG.gn
index 33449ef780019ae8baedfba2dc4e95648f2e8e42..30f42565243ad29ce6d02c6a70ea07263fec5d5a 100644
--- a/build/config/BUILDCONFIG.gn
+++ b/build/config/BUILDCONFIG.gn
@@ -513,6 +513,12 @@ if (is_win) {
 } else if (is_ios) {
   host_toolchain = "//build/toolchain/mac:host_clang"
   set_default_toolchain("//build/toolchain/mac:clang")
+} else if (is_nacl) {
+  # TODO(dpranke): This will need to change when we get NaCl working
+  # on multiple platforms, but this whole block of code (how we define
+  # host_toolchain) needs to be reworked regardless to key off of build_os
+  # and build_cpu_arch rather than the is_* variables.
+  host_toolchain = "//build/toolchain/linux:clang_x64"

[Nick Bray (chromium), 2015/02/05 23:21:45]

Note: this hack would cause the NaCl bots to blow up if we blindly de-duped
BUILDCONFIG.gn, now.  Not sure if there's an AI, but it bothers me a little.

[Dirk Pranke, 2015/02/05 23:52:19]

True. However, I need to rework this whole section of the file in the next
couple days, which will fix this and, I expect, happen far before we attempt to
dedup things.

 }
 
 # ==============================================================================