Allow Thread to initialize COM for Windows consumers who need it

base/threading/com_thread.h

+// 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.
+
+// ComThread is a Thread which, on Windows, initializes COM on the spawned
+// thread when it's created and shuts down COM just before the spawned thread is
+// destroyed.  On non-Windows, ComThread is identical to Thread.  This allows
+// consumers to use ComThread in cross-platform code without having to do any
+// conditional #includes or typedefs of their own.
+
+#ifndef BASE_THREADING_COM_THREAD_H_
+#define BASE_THREADING_COM_THREAD_H_
+
+#include "base/threading/thread.h"
+
+#if defined(OS_WIN)
+#include "base/memory/scoped_ptr.h"
+#include "base/win/scoped_com_initializer.h"
+#endif
+
+namespace base {
+
+class BASE_EXPORT ComThread : public Thread {
+ public:
+#if defined(OS_WIN)
+  ComThread(const char* name, bool use_mta);
+  virtual ~ComThread();
+
+  bool Start();
+
+ protected:
+  virtual void Init() OVERRIDE;     // Creates com_initializer_.
+  virtual void CleanUp() OVERRIDE;  // Destroys com_initializer_.
+
+ private:
+  bool use_mta_;
+  scoped_ptr<win::ScopedCOMInitializer> com_initializer_;
+#else
+  ComThread(const char* name, bool use_mta) : Thread(name) {}
+  virtual ~ComThread() {}
+#endif
+
+  DISALLOW_COPY_AND_ASSIGN(ComThread);
+};
+
+}  // namespace base
+
+#endif  // BASE_THREADING_COM_THREAD_H_