Salient parts of http://codereview.chromium.org/8392042/

content/test/test_browser_thread.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 CONTENT_TEST_TEST_BROWSER_BROWSER_THREAD_H_
+#define CONTENT_TEST_TEST_BROWSER_BROWSER_THREAD_H_
+#pragma once
+
+#include "content/browser/browser_thread_impl.h"
+
+namespace content {
+
+// A BrowserThread for unit tests; this lets unit tests in chrome/
+// create BrowserThread instances.
+class TestBrowserThread : public BrowserThreadImpl {
+ public:
+  explicit TestBrowserThread(ID identifier);
+  TestBrowserThread(ID identifier, MessageLoop* message_loop);
+  virtual ~TestBrowserThread();
+};
+
+}  // namespace content
+
+#endif  // CONTENT_TEST_TEST_BROWSER_BROWSER_THREAD_H_