Preparational work for an upcoming addition of a threadchecking scheme for APM

webrtc/modules/audio_processing/echo_control_mobile_impl.cc

Index: webrtc/modules/audio_processing/echo_control_mobile_impl.cc
diff --git a/webrtc/modules/audio_processing/echo_control_mobile_impl.cc b/webrtc/modules/audio_processing/echo_control_mobile_impl.cc
index 0e898c3028eb1af254db9f7e711954b644d51487..0f966d01fe15064cbf354c3d04351f91eea7529a 100644
--- a/webrtc/modules/audio_processing/echo_control_mobile_impl.cc
+++ b/webrtc/modules/audio_processing/echo_control_mobile_impl.cc
@@ -65,11 +65,14 @@ size_t EchoControlMobile::echo_path_size_bytes() {
     return WebRtcAecm_echo_path_size_bytes();
 }
 
-EchoControlMobileImpl::EchoControlMobileImpl(const AudioProcessing* apm,
-                                             CriticalSectionWrapper* crit)
+EchoControlMobileImpl::EchoControlMobileImpl(
+    const AudioProcessing* apm,
+    CriticalSectionWrapper* crit,
+    const rtc::ThreadChecker* render_thread_checker)
     : ProcessingComponent(),
       apm_(apm),
       crit_(crit),
+      render_thread_checker_(render_thread_checker),
       routing_mode_(kSpeakerphone),
       comfort_noise_enabled_(true),
       external_echo_path_(NULL),
@@ -85,6 +88,7 @@ EchoControlMobileImpl::~EchoControlMobileImpl() {
 }
 
 int EchoControlMobileImpl::ProcessRenderAudio(const AudioBuffer* audio) {
+  RTC_DCHECK(render_thread_checker_->CalledOnValidThread());
   if (!is_component_enabled()) {
     return apm_->kNoError;
   }