Fix double-initialization of CComModule.

base/win/atl_module.h

+// Copyright (c) 2011 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.
+
+#ifndef BASE_WIN_ATL_MODULE_H_
+#define BASE_WIN_ATL_MODULE_H_
+#pragma once
+
+namespace base {
+namespace win {
+
+// Ensure that we have exactly one CComModule registered. It's safe to
+// call this more than once. ATL functions will crash if there's no
+// CComModule registered, or if you try to register two of them, so
+// dynamically registering one if needed makes it much easier for us
+// to support different build configurations like multi-dll without
+// worrying about which side of a module boundary each ATL module object
+// belongs on. Also note that CAppModule is a subclass of CComModule
+// that registers itself (among other things). This function must be
+// implemented in this header file rather than a source file so that
+// it's inlined into the module where it's included, rather than in
+// the "base" module.
+void CreateATLModuleIfNeeded() {
+  if (_pAtlModule == NULL) {
+    static CComModule module;
+    _pAtlModule = &module;
+  }
+}
+
+}  // namespace win
+}  // namespace base
+
+#endif  // BASE_WIN_ATL_MODULE_H_