Fix threading issues in the audio pipeline for WebRTC remoting protocol.

remoting/protocol/webrtc_audio_module.cc

Index: remoting/protocol/webrtc_audio_module.cc
diff --git a/remoting/protocol/webrtc_audio_module.cc b/remoting/protocol/webrtc_audio_module.cc
index fa2d15ec482c5b9f77e2fbf293a23096c50ac092..897b3199670de16a3d64d0bc4570432b8e66c00b 100644
--- a/remoting/protocol/webrtc_audio_module.cc
+++ b/remoting/protocol/webrtc_audio_module.cc
@@ -5,8 +5,10 @@
 #include "remoting/protocol/webrtc_audio_module.h"
 
 #include "base/bind.h"
+#include "base/memory/ptr_util.h"
 #include "base/stl_util.h"
 #include "base/threading/thread_task_runner_handle.h"
+#include "base/timer/timer.h"
 
 namespace remoting {
 namespace protocol {
@@ -502,14 +504,15 @@ int WebrtcAudioModule::GetRecordAudioParameters(
 
 void WebrtcAudioModule::StartPlayoutOnAudioThread() {
   DCHECK(audio_task_runner_->BelongsToCurrentThread());
-  poll_timer_.Start(
+  poll_timer_ = base::MakeUnique<base::RepeatingTimer>();
+  poll_timer_->Start(
       FROM_HERE, kPollInterval,
       base::Bind(&WebrtcAudioModule::PollFromSource, base::Unretained(this)));
 }
 
 void WebrtcAudioModule::StopPlayoutOnAudioThread() {
   DCHECK(audio_task_runner_->BelongsToCurrentThread());
-  poll_timer_.Stop();
+  poll_timer_.reset();
 }
 
 void WebrtcAudioModule::PollFromSource() {