Add ppapi, improve Windows GN build.

build/config/win/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/win/visual_studio_version.gni")
 
 # Compiler setup for the Windows SDK. Applied to all targets.
 config("sdk") {
   # The include path is the stuff returned by the script.
   #include_dirs = msvc_config[0]  TODO(brettw) make this work.
 
   defines = [
     "_ATL_NO_OPENGL",
     "_SECURE_ATL",
     "_WIN32_WINNT=0x0602",
     "_WINDOWS",
     "CERT_CHAIN_PARA_HAS_EXTRA_FIELDS",
-    "NOMINMAX",
     "NTDDI_VERSION=0x06020000",
     "PSAPI_VERSION=1",
     "WIN32",
     "WINVER=0x0602",
   ]
 
   # The Windows SDK include directories must be first. They both have a sal.h,
   # and the SDK one is newer and the SDK uses some newer features from it not
   # present in the Visual Studio one.
   include_dirs = [
@@ skipping 93 matching lines @@
 # Lean and mean ----------------------------------------------------------------
 
 # Some third party code might not compile with WIN32_LEAN_AND_MEAN so we have
 # to have a separate config for it. Remove this config from your target to
 # get the "bloaty and accomodating" version of windows.h.
 config("lean_and_mean") {
   defines = [
     "WIN32_LEAN_AND_MEAN",
   ]
 }
+
+# Nominmax --------------------------------------------------------------------
+
+# Some third party code defines NOMINMAX before including windows.h, which
+# then causes warnings when it's been previously defined on the command line.
+# For such targets, this config can be removed.
+
+config("nominmax") {
+  defines = [
+    "NOMINMAX",
+  ]
+}