Add WARN_UNUSED_RESULT to scoped_refptr::release.

chrome/browser/sync/glue/browser_thread_model_worker_unittest.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/bind.h"
 #include "base/callback.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
 #include "base/message_loop.h"
 #include "base/test/test_timeouts.h"
@@ skipping 60 matching lines @@
         BrowserThread::IO, FROM_HERE, MessageLoop::QuitClosure());
   }
 
  protected:
   virtual void SetUp() {
     db_thread_.Start();
     worker_ = new DatabaseModelWorker();
   }
 
   virtual void Teardown() {
-    worker_.release();
+    worker_ = NULL;
     db_thread_.Stop();
   }
 
  private:
   bool did_do_work_;
   scoped_refptr<BrowserThreadModelWorker> worker_;
   OneShotTimer<SyncBrowserThreadModelWorkerTest> timer_;
 
   content::TestBrowserThread db_thread_;
   MessageLoopForIO io_loop_;
   content::TestBrowserThread io_thread_;
 
   base::WeakPtrFactory<SyncBrowserThreadModelWorkerTest> weak_factory_;
 };
 
 TEST_F(SyncBrowserThreadModelWorkerTest, DoesWorkOnDatabaseThread) {
   MessageLoop::current()->PostTask(FROM_HERE,
       base::Bind(&SyncBrowserThreadModelWorkerTest::ScheduleWork,
                  factory()->GetWeakPtr()));
   MessageLoop::current()->Run();
   EXPECT_TRUE(did_do_work());
 }
 
 }  // namespace
 
 }  // namespace browser_sync