Add OpenVR SDK to third_party

third_party/openvr/BUILD.gn

+# Copyright 2017 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.
+
+loadable_module("openvr") {
+  output_name = "openvr_api"
+
+  # Some ascii versions of Windows APIs are used in this code.
+  configs -= [ "//build/config/win:unicode" ]
+
+  # This code can be built using internal OpenVR functionality, but the internal
+  # dependencies aren't available to us.
+  defines = [ "VR_API_PUBLIC" ]
+
+  sources = [
+    "src/src/jsoncpp.cpp",
+    "src/src/openvr_api_public.cpp",
+    "src/src/vrcommon/dirtools_public.cpp",
+    "src/src/vrcommon/envvartools_public.cpp",
+    "src/src/vrcommon/hmderrors_public.cpp",
+    "src/src/vrcommon/pathtools_public.cpp",
+    "src/src/vrcommon/sharedlibtools_public.cpp",
+    "src/src/vrcommon/strtools_public.cpp",
+    "src/src/vrcommon/vrpathregistry_public.cpp",
+  ]
+
+  include_dirs = [
+    "src/headers",
+    "src/src",
+    "src/src/json",
+    "src/src/vrcommon",
+  ]
+}