base: Fix DCHECK when thread creation fails

base/message_loop/message_loop_unittest.cc

 // Copyright 2013 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 <stddef.h>
 #include <stdint.h>
 
 #include <vector>
 
 #include "base/bind.h"
@@ skipping 1023 matching lines @@
   scoped_refptr<SingleThreadTaskRunner> original_runner(loop.task_runner());
   loop.SetTaskRunner(new_runner);
 
   scoped_refptr<Foo> foo(new Foo());
   original_runner->PostTask(FROM_HERE,
                             Bind(&Foo::Test1ConstRef, foo.get(), "a"));
   loop.RunUntilIdle();
   EXPECT_EQ(1, foo->test_count());
 }
 
+TEST(MessageLoopTest, DeleteUnboundLoop) {
+  // It should be possible to delete an unbound message loop on a thread which
+  // already has another active loop. This happens when thread creation fails.
+  MessageLoop loop;
+  scoped_ptr<MessageLoop> unbound_loop(MessageLoop::CreateUnbound(
+      MessageLoop::TYPE_DEFAULT, MessageLoop::MessagePumpFactoryCallback()));
+  unbound_loop.reset();
+  EXPECT_EQ(&loop, MessageLoop::current());
+  EXPECT_EQ(loop.task_runner(), ThreadTaskRunnerHandle::Get());
+}
+
 }  // namespace base