Enable WPO for the x64 Official builds.

chrome/installer/mini_installer/BUILD.gn

Index: chrome/installer/mini_installer/BUILD.gn
diff --git a/chrome/installer/mini_installer/BUILD.gn b/chrome/installer/mini_installer/BUILD.gn
index a48f94ac7943648e5085d5f4164c1a87721e8853..aaa51672b0dfbd160c9fba33cfd0b141daa02ce8 100644
--- a/chrome/installer/mini_installer/BUILD.gn
+++ b/chrome/installer/mini_installer/BUILD.gn
@@ -167,6 +167,7 @@ executable("mini_installer") {
   # This target is special so we manually override most linker flags and
   # specify our own to keep the size down.
   configs -= [
+    "//build/config/compiler:default_optimization",

[grt (UTC plus 2), 2016/06/01 18:46:59]

i don't get this. why?

[Sébastien Marchand, 2016/06/01 19:16:31]

It's because the default optimization now adds the /GL compiler flag for
Official x64, which doesn't work with the mini_installer. I haven't added a
comment because I thought that the general comment for this group was clear
enough ?

The alternative would be to depend on the 'optimize_no_wpo' config like we do in
ffmpeg:
https://code.google.com/p/chromium/codesearch#chromium/src/third_party/ffmpeg...

Which solution do you prefer ?

[brucedawson, 2016/06/03 00:47:53]

Well, as sometimes happens the reviewers successfully convinced the CL author to
do the wrong thing. I think that default_optimization was correct. When building
a debug version of the mini_installer today I hit this warning:

[4 processes, 6357/6386 @ 4.8/s : 1322.877s ] LINK mini_installer.exe
LINK : warning LNK4075: ignoring '/INCREMENTAL' due to '/OPT:ICF' specification

Do we need a default_optimization_no_wpo config?

[Sébastien Marchand, 2016/06/03 01:13:18]

I think that this will add too much complexity to our build system, I'd suggest
to simply put the '//build/config/compiler:optimize_no_wpo' config behind a 'if
(!is_debug)' flag ? (in this file). This will be closer to what's being done in
the default_optimization config:
https://code.google.com/p/chromium/codesearch#chromium/src/build/config/compi...

     "//build/config:executable_config",
     "//build/config/win:console",
   ]