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diff --git a/net/base/test_completion_callback_unittest.cc b/net/base/test_completion_callback_unittest.cc
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+++ b/net/base/test_completion_callback_unittest.cc
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+// Copyright (c) 2006-2008 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.
+
+// Illustrates how to use worker threads that issue completion callbacks
+
+#include "testing/gtest/include/gtest/gtest.h"
+#include "net/base/completion_callback.h"
+#include "net/base/test_completion_callback.h"
+#include "base/worker_pool.h"
+
+using net::CompletionCallback;
+
+const int kMagicResult = 8888;
+
+// ExampleEmployer is a toy version of HostResolver 
+// TODO: restore damage done in extracting example from real code
+// (e.g. bring back real destructor, bring back comments)
+class ExampleEmployer {
+ public:
+  ExampleEmployer();
+  ~ExampleEmployer();
+
+  // Do some imaginary work on a worker thread;
+  // when done, worker posts callback on the original thread.
+  // Returns true on success
+  bool DoSomething(CompletionCallback* callback);
+
+ private:
+  class ExampleWorker;
+  friend class ExampleWorker;
+  scoped_refptr<ExampleWorker> request_;
+  DISALLOW_COPY_AND_ASSIGN(ExampleEmployer);
+};
+
+// Helper class; this is how ExampleEmployer puts work on a different thread
+class ExampleEmployer::ExampleWorker 
+    : public base::RefCountedThreadSafe<ExampleWorker> {
+ public:
+  ExampleWorker(ExampleEmployer* employer, CompletionCallback* callback)
+      : callback_(callback),
+	employer_(employer),
+	origin_loop_(MessageLoop::current()) {
+  }
+  void DoWork();
+  void DoCallback();
+ private:
+  // Only used on the origin thread (where DoSomething was called).
+  ExampleEmployer* employer_;
+  CompletionCallback* callback_;
+  // Used to post ourselves onto the origin thread.
+  Lock origin_loop_lock_;
+  MessageLoop* origin_loop_;
+};
+
+void ExampleEmployer::ExampleWorker::DoWork() {
+  // Running on the worker thread
+  // In a real worker thread, some work would be done here.
+  // Pretend it is, and send the completion callback.
+  Task* reply = NewRunnableMethod(this, &ExampleWorker::DoCallback);
+
+  // The origin loop could go away while we are trying to post to it, so we
+  // need to call its PostTask method inside a lock.  See ~ExampleEmployer.
+  {
+    AutoLock locked(origin_loop_lock_);
+    if (origin_loop_) {
+      origin_loop_->PostTask(FROM_HERE, reply);
+      reply = NULL;
+    }
+  }
+  
+  // Does nothing if it got posted.
+  delete reply;
+}
+
+void ExampleEmployer::ExampleWorker::DoCallback() {
+  // Running on the origin thread.
+
+  // Drop the employer_'s reference to us.  Do this before running the
+  // callback since the callback might result in the employer being
+  // destroyed.
+  employer_->request_ = NULL;
+
+  callback_->Run(kMagicResult);
+}
+
+ExampleEmployer::ExampleEmployer() {
+}
+
+ExampleEmployer::~ExampleEmployer() {
+}
+
+bool ExampleEmployer::DoSomething(CompletionCallback* callback) {
+  DCHECK(!request_) << "already in use";
+
+  request_ = new ExampleWorker(this, callback);
+
+  // Dispatch to worker thread...
+  if (!WorkerPool::PostTask(FROM_HERE,
+          NewRunnableMethod(request_.get(), &ExampleWorker::DoWork), true)) {
+    NOTREACHED();
+    request_ = NULL;
+    return false;
+  }
+
+  return true;
+}
+
+TEST(TestCompletionCallbackTest, Simple) {
+  ExampleEmployer boss;
+  TestCompletionCallback callback;
+  bool queued = boss.DoSomething(&callback);
+  EXPECT_EQ(queued, true);
+  int result = callback.WaitForResult();
+  EXPECT_EQ(result, kMagicResult);
+}
+
+// TODO: test deleting ExampleEmployer while work outstanding