Fix hangs & crashes in teardown-during-Seek.

content/renderer/media/audio_renderer_impl.cc

Index: content/renderer/media/audio_renderer_impl.cc
diff --git a/content/renderer/media/audio_renderer_impl.cc b/content/renderer/media/audio_renderer_impl.cc
index 754b7e006424cd87604977b7d0435b3cb68c2ab8..2c131eca0ae53cafd8ace2db696a749fa1daa370 100644
--- a/content/renderer/media/audio_renderer_impl.cc
+++ b/content/renderer/media/audio_renderer_impl.cc
@@ -99,19 +99,28 @@ bool AudioRendererImpl::OnInitialize(int bits_per_channel,
 }
 
 void AudioRendererImpl::OnStop() {
-  base::AutoLock auto_lock(lock_);
-  if (stopped_)
-    return;
-  stopped_ = true;
+  // Since joining with the audio thread can acquire lock_, we make sure to
+  // Join() with it not under lock.
+  base::DelegateSimpleThread* audio_thread = NULL;
+  {
+    base::AutoLock auto_lock(lock_);
+    if (stopped_)
+      return;
+    stopped_ = true;
 
-  ChildProcess::current()->io_message_loop()->PostTask(
-      FROM_HERE,
-      base::Bind(&AudioRendererImpl::DestroyTask, this));
+    DCHECK_EQ(!audio_thread_.get(), !socket_.get());
+    if (socket_.get())
+      socket_->Close();
+    if (audio_thread_.get())
+      audio_thread = audio_thread_.get();
 
-  if (audio_thread_.get()) {
-    socket_->Close();
-    audio_thread_->Join();
+    ChildProcess::current()->io_message_loop()->PostTask(
+        FROM_HERE,
+        base::Bind(&AudioRendererImpl::DestroyTask, this));
   }
+
+  if (audio_thread)
+    audio_thread->Join();
 }
 
 void AudioRendererImpl::NotifyDataAvailableIfNecessary() {
@@ -456,6 +465,7 @@ void AudioRendererImpl::WillDestroyCurrentMessageLoop() {
 // Our audio thread runs here. We receive requests for more data and send it
 // on this thread.
 void AudioRendererImpl::Run() {
+  DCHECK_EQ(kLowLatency, latency_type_);
   audio_thread_->SetThreadPriority(base::kThreadPriority_RealtimeAudio);
 
   int bytes;