Allow Thread to initialize COM for Windows consumers who need it

base/threading/com_thread_win.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 "base/threading/com_thread.h"
+
+namespace base {
+
+bool ComThread::Start() {
+  if (!use_mta_)
+    return Thread::Start();
+
+  // STA COM objects require a UI message loop in order to pump Windows
+  // messages, which they may use for various purposes.
+  Thread::Options thread_options(MessageLoop::TYPE_UI, 0);
+  return StartWithOptions(thread_options);
+}
+
+void ComThread::Init() {
+  com_initializer_.reset(use_mta_ ?
+      new win::ScopedCOMInitializer(win::ScopedCOMInitializer::kMTA) :
+      new win::ScopedCOMInitializer());
+}
+
+void ComThread::CleanUp() {
+  com_initializer_.reset();
+}
+
+}  // namespace base