Only add swiftshader/include to include_dirs on Windows.

ui/gl/init/BUILD.gn

 # Copyright 2016 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/ui.gni")
 
 component("init") {
   output_name = "gl_init"
 
   public = [
     "gl_factory.h",
   ]
 
   sources = [
     "gl_factory.cc",
     "gl_init_export.h",
     "gl_initializer.h",
   ]
   defines = [ "GL_INIT_IMPLEMENTATION" ]
 
-  include_dirs = [ "//third_party/swiftshader/include" ]
-
   deps = [
     "//base",
     "//ui/gfx",
   ]
 
   public_deps = [
     "//ui/gl",
   ]
 
   if (is_android) {
     sources += [
       "gl_factory_android.cc",
       "gl_initializer_android.cc",
     ]
   } else if (is_win) {
+    include_dirs = [ "//third_party/swiftshader/include" ]
+
     sources += [
       "gl_factory_win.cc",
       "gl_initializer_win.cc",
     ]
 
     libs = [ "dwmapi.lib" ]
     ldflags = [ "/DELAYLOAD:dwmapi.dll" ]
   } else if (is_mac) {
     sources += [
       "gl_factory_mac.cc",
@@ skipping 10 matching lines @@
     deps += [ "//ui/gfx/x" ]
   } else if (use_ozone) {
     sources += [
       "gl_factory_ozone.cc",
       "gl_initializer_ozone.cc",
     ]
 
     deps += [ "//ui/ozone" ]
   }
 }