Metro/HiDPI: Use metro resource pak in metro mode

ui/base/win/metro.cc

+// Copyright (c) 2012 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.
+
+#include "ui/base/win/metro.h"
+
+#include <string>
+#include <windows.h>
+
+namespace ui {
+
+bool IsInMetroMode() {
+  const char* kMetroModeEnvVar = "CHROME_METRO_DLL";
+  char buffer[2];
+  if (!::GetEnvironmentVariableA(kMetroModeEnvVar, buffer, arraysize(buffer)))
+    return false;
+  return buffer == std::string("1");
+}
+
+}  // namespace ui