Use scoped_ptr for ThreadWrapper::CreateThread.

BUG=
R=henrika@webrtc.org, pbos@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/45799004

Cr-Commit-Position: refs/heads/master@{#8794}
git-svn-id: http://webrtc.googlecode.com/svn/trunk@8794 4adac7df-926f-26a2-2b94-8c16560cd09d
diff --git a/webrtc/modules/utility/source/process_thread_impl.cc b/webrtc/modules/utility/source/process_thread_impl.cc
index 42c5924..33a1c4f 100644
--- a/webrtc/modules/utility/source/process_thread_impl.cc
+++ b/webrtc/modules/utility/source/process_thread_impl.cc
@@ -69,8 +69,8 @@
   for (ModuleCallback& m : modules_)
     m.module->ProcessThreadAttached(this);
 
-  thread_.reset(ThreadWrapper::CreateThread(
-      &ProcessThreadImpl::Run, this, kNormalPriority, "ProcessThread"));
+  thread_ = ThreadWrapper::CreateThread(
+      &ProcessThreadImpl::Run, this, kNormalPriority, "ProcessThread");
   CHECK(thread_->Start());
 }