1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #include "media/audio/scoped_loop_observer.h" 6 7 #include "base/bind.h" 8 #include "base/synchronization/waitable_event.h" 9 10 namespace media { 11 12 ScopedLoopObserver::ScopedLoopObserver( 13 const scoped_refptr<base::MessageLoopProxy>& loop) 14 : loop_(loop) { 15 ObserveLoopDestruction(true, NULL); 16 } 17 18 ScopedLoopObserver::~ScopedLoopObserver() { 19 ObserveLoopDestruction(false, NULL); 20 } 21 22 void ScopedLoopObserver::ObserveLoopDestruction(bool enable, 23 base::WaitableEvent* done) { 24 // Note: |done| may be NULL. 25 if (loop_->BelongsToCurrentThread()) { 26 base::MessageLoop* loop = base::MessageLoop::current(); 27 if (enable) { 28 loop->AddDestructionObserver(this); 29 } else { 30 loop->RemoveDestructionObserver(this); 31 } 32 } else { 33 base::WaitableEvent event(false, false); 34 if (loop_->PostTask(FROM_HERE, 35 base::Bind(&ScopedLoopObserver::ObserveLoopDestruction, 36 base::Unretained(this), enable, &event))) { 37 event.Wait(); 38 } else { 39 // The message loop's thread has already terminated, so no need to wait. 40 } 41 } 42 43 if (done) 44 done->Signal(); 45 } 46 47 } // namespace media. 48
