Revert "Reduce locking in VideoReceiver and check the threading model."

This reverts commit c75f1e45093a8d5cc62937c7708b87aa5c5bf0b0.

Reason for revert: Breaking internal project

Original change's description:
> Reduce locking in VideoReceiver and check the threading model.
> 
> Note: This is a subset of code that was previously reviewed here:
>   - https://codereview.webrtc.org/2764573002/
> 
> * Added two notification methods, DecoderThreadStarting() and DecoderThreadStopped()
>   * Allows us to establish a period when the decoder thread is not running and it is
>     safe to modify variables such as callbacks, that are only read when the decoder
>     thread is running.
>   * Allows us to DCHECK thread guarantees/correctness.
>   * Allows synchronizing callbacks from the module process thread and have them only
>     active while the decoder thread is running.
>   * The above, allows us to establish two modes for the thread,
>     single-threaded-mutable and multi-threaded-const.
>   * Using that knowledge, we can remove |receive_crit_| as well as locking for a
>     number of member variables.
> * Removed |VCMFrameBuffer _frameFromFile| (unused).
> * Clean up several of my TODOs
> 
> Bug: webrtc:7361, chromium:695438
> Change-Id: Id0048ee9624f76103c088d02825eb5c0d6c8913c
> Reviewed-on: https://webrtc-review.googlesource.com/55000
> Commit-Queue: Tommi <tommi@webrtc.org>
> Reviewed-by: Philip Eliasson <philipel@webrtc.org>
> Cr-Commit-Position: refs/heads/master@{#22133}

TBR=tommi@webrtc.org,philipel@webrtc.org

Change-Id: I4d78e8b2c05b36e1a3f64cb38d652579b3a23f22
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: webrtc:7361, chromium:695438
Reviewed-on: https://webrtc-review.googlesource.com/56280
Reviewed-by: Lu Liu <lliuu@webrtc.org>
Commit-Queue: Lu Liu <lliuu@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#22141}
diff --git a/modules/video_coding/video_coding_impl.h b/modules/video_coding/video_coding_impl.h
index 3b692d1..8a442c8 100644
--- a/modules/video_coding/video_coding_impl.h
+++ b/modules/video_coding/video_coding_impl.h
@@ -143,7 +143,7 @@
                 VCMTiming* timing,
                 NackSender* nack_sender = nullptr,
                 KeyFrameRequestSender* keyframe_request_sender = nullptr);
-  ~VideoReceiver() override;
+  ~VideoReceiver();
 
   int32_t RegisterReceiveCodec(const VideoCodec* receiveCodec,
                                int32_t numberOfCores,
@@ -161,6 +161,9 @@
 
   int32_t Decode(const webrtc::VCMEncodedFrame* frame);
 
+  // Called on the decoder thread when thread is exiting.
+  void DecodingStopped();
+
   int32_t IncomingPacket(const uint8_t* incomingPayload,
                          size_t payloadLength,
                          const WebRtcRTPHeader& rtpInfo);
@@ -185,72 +188,41 @@
 
   int64_t TimeUntilNextProcess() override;
   void Process() override;
-  void ProcessThreadAttached(ProcessThread* process_thread) override;
 
   void TriggerDecoderShutdown();
 
-  // Notification methods that are used to check our internal state and validate
-  // threading assumptions. These are called by VideoReceiveStream.
-  // See |IsDecoderThreadRunning()| for more details.
-  void DecoderThreadStarting();
-  void DecoderThreadStopped();
-
  protected:
-  int32_t Decode(const webrtc::VCMEncodedFrame& frame);
+  int32_t Decode(const webrtc::VCMEncodedFrame& frame)
+      RTC_EXCLUSIVE_LOCKS_REQUIRED(receive_crit_);
   int32_t RequestKeyFrame();
 
  private:
-  // Used for DCHECKing thread correctness.
-  // In build where DCHECKs are enabled, will return false before
-  // DecoderThreadStarting is called, then true until DecoderThreadStopped
-  // is called.
-  // In builds where DCHECKs aren't enabled, it will return true.
-  bool IsDecoderThreadRunning();
-
-  rtc::ThreadChecker construction_thread_checker_;
-  rtc::ThreadChecker decoder_thread_checker_;
-  rtc::ThreadChecker module_thread_checker_;
+  rtc::ThreadChecker construction_thread_;
   Clock* const clock_;
   rtc::CriticalSection process_crit_;
+  rtc::CriticalSection receive_crit_;
   VCMTiming* _timing;
   VCMReceiver _receiver;
   VCMDecodedFrameCallback _decodedFrameCallback;
+  VCMFrameTypeCallback* _frameTypeCallback RTC_GUARDED_BY(process_crit_);
+  VCMReceiveStatisticsCallback* _receiveStatsCallback
+      RTC_GUARDED_BY(process_crit_);
+  VCMPacketRequestCallback* _packetRequestCallback
+      RTC_GUARDED_BY(process_crit_);
 
-  // These callbacks are set on the construction thread before being attached
-  // to the module thread or decoding started, so a lock is not required.
-  VCMFrameTypeCallback* _frameTypeCallback;
-  VCMReceiveStatisticsCallback* _receiveStatsCallback;
-  VCMPacketRequestCallback* _packetRequestCallback;
-
-  // Used on both the module and decoder thread.
+  VCMFrameBuffer _frameFromFile;
   bool _scheduleKeyRequest RTC_GUARDED_BY(process_crit_);
   bool drop_frames_until_keyframe_ RTC_GUARDED_BY(process_crit_);
+  size_t max_nack_list_size_ RTC_GUARDED_BY(process_crit_);
 
-  // Modified on the construction thread while not attached to the process
-  // thread.  Once attached to the process thread, its value is only read
-  // so a lock is not required.
-  size_t max_nack_list_size_;
+  VCMDecoderDataBase _codecDataBase RTC_GUARDED_BY(receive_crit_);
+  EncodedImageCallback* pre_decode_image_callback_;
 
-  // Callbacks are set before the decoder thread starts.
-  // Once the decoder thread has been started, usage of |_codecDataBase| moves
-  // over to the decoder thread.
-  VCMDecoderDataBase _codecDataBase;
-  EncodedImageCallback* const pre_decode_image_callback_;
-
-  VCMProcessTimer _receiveStatsTimer RTC_GUARDED_BY(module_thread_checker_);
-  VCMProcessTimer _retransmissionTimer RTC_GUARDED_BY(module_thread_checker_);
-  VCMProcessTimer _keyRequestTimer RTC_GUARDED_BY(module_thread_checker_);
-  QpParser qp_parser_ RTC_GUARDED_BY(decoder_thread_checker_);
-  ThreadUnsafeOneTimeEvent first_frame_received_
-      RTC_GUARDED_BY(decoder_thread_checker_);
-  // Modified on the construction thread. Can be read without a lock and assumed
-  // to be non-null on the module and decoder threads.
-  ProcessThread* process_thread_ = nullptr;
-  bool is_attached_to_process_thread_
-      RTC_GUARDED_BY(construction_thread_checker_) = false;
-#if RTC_DCHECK_IS_ON
-  bool decoder_thread_is_running_ = false;
-#endif
+  VCMProcessTimer _receiveStatsTimer;
+  VCMProcessTimer _retransmissionTimer;
+  VCMProcessTimer _keyRequestTimer;
+  QpParser qp_parser_;
+  ThreadUnsafeOneTimeEvent first_frame_received_;
 };
 
 }  // namespace vcm
diff --git a/modules/video_coding/video_receiver.cc b/modules/video_coding/video_receiver.cc
index 25b2908..038c523 100644
--- a/modules/video_coding/video_receiver.cc
+++ b/modules/video_coding/video_receiver.cc
@@ -10,14 +10,12 @@
 
 #include "common_types.h"  // NOLINT(build/include)
 #include "common_video/libyuv/include/webrtc_libyuv.h"
-#include "modules/utility/include/process_thread.h"
 #include "modules/video_coding/encoded_frame.h"
 #include "modules/video_coding/include/video_codec_interface.h"
 #include "modules/video_coding/jitter_buffer.h"
 #include "modules/video_coding/packet.h"
 #include "modules/video_coding/video_coding_impl.h"
 #include "rtc_base/checks.h"
-#include "rtc_base/location.h"
 #include "rtc_base/logging.h"
 #include "rtc_base/trace_event.h"
 #include "system_wrappers/include/clock.h"
@@ -42,6 +40,7 @@
       _frameTypeCallback(nullptr),
       _receiveStatsCallback(nullptr),
       _packetRequestCallback(nullptr),
+      _frameFromFile(),
       _scheduleKeyRequest(false),
       drop_frames_until_keyframe_(false),
       max_nack_list_size_(0),
@@ -49,23 +48,18 @@
       pre_decode_image_callback_(pre_decode_image_callback),
       _receiveStatsTimer(1000, clock_),
       _retransmissionTimer(10, clock_),
-      _keyRequestTimer(500, clock_) {
-  decoder_thread_checker_.DetachFromThread();
-  module_thread_checker_.DetachFromThread();
-}
+      _keyRequestTimer(500, clock_) {}
 
-VideoReceiver::~VideoReceiver() {
-  RTC_DCHECK_RUN_ON(&construction_thread_checker_);
-}
+VideoReceiver::~VideoReceiver() {}
 
 void VideoReceiver::Process() {
-  RTC_DCHECK_RUN_ON(&module_thread_checker_);
   // Receive-side statistics
 
   // TODO(philipel): Remove this if block when we know what to do with
   //                 ReceiveStatisticsProxy::QualitySample.
   if (_receiveStatsTimer.TimeUntilProcess() == 0) {
     _receiveStatsTimer.Processed();
+    rtc::CritScope cs(&process_crit_);
     if (_receiveStatsCallback != nullptr) {
       _receiveStatsCallback->OnReceiveRatesUpdated(0, 0);
     }
@@ -74,10 +68,10 @@
   // Key frame requests
   if (_keyRequestTimer.TimeUntilProcess() == 0) {
     _keyRequestTimer.Processed();
-    bool request_key_frame = _frameTypeCallback != nullptr;
-    if (request_key_frame) {
+    bool request_key_frame = false;
+    {
       rtc::CritScope cs(&process_crit_);
-      request_key_frame = _scheduleKeyRequest;
+      request_key_frame = _scheduleKeyRequest && _frameTypeCallback != nullptr;
     }
     if (request_key_frame)
       RequestKeyFrame();
@@ -88,8 +82,13 @@
   // disabled when NACK is off.
   if (_retransmissionTimer.TimeUntilProcess() == 0) {
     _retransmissionTimer.Processed();
-    bool callback_registered = _packetRequestCallback != nullptr;
-    uint16_t length = max_nack_list_size_;
+    bool callback_registered = false;
+    uint16_t length;
+    {
+      rtc::CritScope cs(&process_crit_);
+      length = max_nack_list_size_;
+      callback_registered = _packetRequestCallback != nullptr;
+    }
     if (callback_registered && length > 0) {
       // Collect sequence numbers from the default receiver.
       bool request_key_frame = false;
@@ -108,19 +107,7 @@
   }
 }
 
-void VideoReceiver::ProcessThreadAttached(ProcessThread* process_thread) {
-  RTC_DCHECK_RUN_ON(&construction_thread_checker_);
-  if (process_thread) {
-    is_attached_to_process_thread_ = true;
-    RTC_DCHECK(!process_thread_ || process_thread_ == process_thread);
-    process_thread_ = process_thread;
-  } else {
-    is_attached_to_process_thread_ = false;
-  }
-}
-
 int64_t VideoReceiver::TimeUntilNextProcess() {
-  RTC_DCHECK_RUN_ON(&module_thread_checker_);
   int64_t timeUntilNextProcess = _receiveStatsTimer.TimeUntilProcess();
   if (_receiver.NackMode() != kNoNack) {
     // We need a Process call more often if we are relying on
@@ -135,7 +122,7 @@
 }
 
 int32_t VideoReceiver::SetReceiveChannelParameters(int64_t rtt) {
-  RTC_DCHECK_RUN_ON(&module_thread_checker_);
+  rtc::CritScope cs(&receive_crit_);
   _receiver.UpdateRtt(rtt);
   return 0;
 }
@@ -155,6 +142,7 @@
     }
 
     case kProtectionNackFEC: {
+      rtc::CritScope cs(&receive_crit_);
       RTC_DCHECK(enable);
       _receiver.SetNackMode(kNack,
                             media_optimization::kLowRttNackMs,
@@ -177,22 +165,20 @@
 // ready for rendering.
 int32_t VideoReceiver::RegisterReceiveCallback(
     VCMReceiveCallback* receiveCallback) {
-  RTC_DCHECK_RUN_ON(&construction_thread_checker_);
-  RTC_DCHECK(!IsDecoderThreadRunning());
-  // This value is set before the decoder thread starts and unset after
-  // the decoder thread has been stopped.
+  RTC_DCHECK(construction_thread_.CalledOnValidThread());
+  // TODO(tommi): Callback may be null, but only after the decoder thread has
+  // been stopped. Use the signal we now get that tells us when the decoder
+  // thread isn't running, to DCHECK that the method is never called while it
+  // is. Once we're confident, we can remove the lock.
+  rtc::CritScope cs(&receive_crit_);
   _decodedFrameCallback.SetUserReceiveCallback(receiveCallback);
   return VCM_OK;
 }
 
 int32_t VideoReceiver::RegisterReceiveStatisticsCallback(
     VCMReceiveStatisticsCallback* receiveStats) {
-  RTC_DCHECK_RUN_ON(&construction_thread_checker_);
-  RTC_DCHECK(!IsDecoderThreadRunning() && !is_attached_to_process_thread_);
-  // |_receiver| is used on both the decoder and module threads.
-  // However, since we make sure that we never do anything on the module thread
-  // when the decoder thread is not running, we don't need a lock for the
-  // |_receiver| or |_receiveStatsCallback| here.
+  RTC_DCHECK(construction_thread_.CalledOnValidThread());
+  rtc::CritScope cs(&process_crit_);
   _receiver.RegisterStatsCallback(receiveStats);
   _receiveStatsCallback = receiveStats;
   return VCM_OK;
@@ -201,8 +187,10 @@
 // Register an externally defined decoder object.
 void VideoReceiver::RegisterExternalDecoder(VideoDecoder* externalDecoder,
                                             uint8_t payloadType) {
-  RTC_DCHECK_RUN_ON(&construction_thread_checker_);
-  RTC_DCHECK(!IsDecoderThreadRunning());
+  RTC_DCHECK(construction_thread_.CalledOnValidThread());
+  // TODO(tommi): This method must be called when the decoder thread is not
+  // running.  Do we need a lock in that case?
+  rtc::CritScope cs(&receive_crit_);
   if (externalDecoder == nullptr) {
     RTC_CHECK(_codecDataBase.DeregisterExternalDecoder(payloadType));
     return;
@@ -213,91 +201,53 @@
 // Register a frame type request callback.
 int32_t VideoReceiver::RegisterFrameTypeCallback(
     VCMFrameTypeCallback* frameTypeCallback) {
-  RTC_DCHECK_RUN_ON(&construction_thread_checker_);
-  RTC_DCHECK(!IsDecoderThreadRunning() && !is_attached_to_process_thread_);
-  // This callback is used on the module thread, but since we don't get
-  // callbacks on the module thread while the decoder thread isn't running
-  // (and this function must not be called when the decoder is running),
-  // we don't need a lock here.
+  rtc::CritScope cs(&process_crit_);
   _frameTypeCallback = frameTypeCallback;
   return VCM_OK;
 }
 
 int32_t VideoReceiver::RegisterPacketRequestCallback(
     VCMPacketRequestCallback* callback) {
-  RTC_DCHECK_RUN_ON(&construction_thread_checker_);
-  RTC_DCHECK(!IsDecoderThreadRunning() && !is_attached_to_process_thread_);
-  // This callback is used on the module thread, but since we don't get
-  // callbacks on the module thread while the decoder thread isn't running
-  // (and this function must not be called when the decoder is running),
-  // we don't need a lock here.
+  rtc::CritScope cs(&process_crit_);
   _packetRequestCallback = callback;
   return VCM_OK;
 }
 
 void VideoReceiver::TriggerDecoderShutdown() {
-  RTC_DCHECK_RUN_ON(&construction_thread_checker_);
-  RTC_DCHECK(IsDecoderThreadRunning());
+  RTC_DCHECK(construction_thread_.CalledOnValidThread());
   _receiver.TriggerDecoderShutdown();
 }
 
-void VideoReceiver::DecoderThreadStarting() {
-  RTC_DCHECK_RUN_ON(&construction_thread_checker_);
-  RTC_DCHECK(!IsDecoderThreadRunning());
-  if (process_thread_ && !is_attached_to_process_thread_) {
-    process_thread_->RegisterModule(this, RTC_FROM_HERE);
-  }
-#if RTC_DCHECK_IS_ON
-  decoder_thread_is_running_ = true;
-#endif
-}
-
-void VideoReceiver::DecoderThreadStopped() {
-  RTC_DCHECK_RUN_ON(&construction_thread_checker_);
-  RTC_DCHECK(IsDecoderThreadRunning());
-  if (process_thread_ && is_attached_to_process_thread_) {
-    process_thread_->DeRegisterModule(this);
-  }
-#if RTC_DCHECK_IS_ON
-  decoder_thread_is_running_ = false;
-  decoder_thread_checker_.DetachFromThread();
-#endif
-}
-
 // Decode next frame, blocking.
 // Should be called as often as possible to get the most out of the decoder.
 int32_t VideoReceiver::Decode(uint16_t maxWaitTimeMs) {
-  RTC_DCHECK_RUN_ON(&decoder_thread_checker_);
-  VCMEncodedFrame* frame = _receiver.FrameForDecoding(
-      maxWaitTimeMs, _codecDataBase.PrefersLateDecoding());
+  bool prefer_late_decoding = false;
+  {
+    // TODO(tommi): Chances are that this lock isn't required.
+    rtc::CritScope cs(&receive_crit_);
+    prefer_late_decoding = _codecDataBase.PrefersLateDecoding();
+  }
+
+  VCMEncodedFrame* frame =
+      _receiver.FrameForDecoding(maxWaitTimeMs, prefer_late_decoding);
 
   if (!frame)
     return VCM_FRAME_NOT_READY;
 
-  bool drop_frame = false;
   {
     rtc::CritScope cs(&process_crit_);
     if (drop_frames_until_keyframe_) {
       // Still getting delta frames, schedule another keyframe request as if
       // decode failed.
       if (frame->FrameType() != kVideoFrameKey) {
-        drop_frame = true;
         _scheduleKeyRequest = true;
-        // TODO(tommi): Consider if we could instead post a task to the module
-        // thread and call RequestKeyFrame directly. Here we call WakeUp so that
-        // TimeUntilNextProcess() gets called straight away.
-        process_thread_->WakeUp(this);
-      } else {
-        drop_frames_until_keyframe_ = false;
+        _receiver.ReleaseFrame(frame);
+        return VCM_FRAME_NOT_READY;
       }
+      drop_frames_until_keyframe_ = false;
     }
   }
 
-  if (drop_frame) {
-    _receiver.ReleaseFrame(frame);
-    return VCM_FRAME_NOT_READY;
-  }
-
   if (pre_decode_image_callback_) {
     EncodedImage encoded_image(frame->EncodedImage());
     int qp = -1;
@@ -308,6 +258,7 @@
                                                frame->CodecSpecific(), nullptr);
   }
 
+  rtc::CritScope cs(&receive_crit_);
   // If this frame was too late, we should adjust the delay accordingly
   _timing->UpdateCurrentDelay(frame->RenderTimeMs(),
                               clock_->TimeInMilliseconds());
@@ -327,7 +278,7 @@
 // TODO(philipel): Clean up among the Decode functions as we replace
 //                 VCMEncodedFrame with FrameObject.
 int32_t VideoReceiver::Decode(const webrtc::VCMEncodedFrame* frame) {
-  RTC_DCHECK_RUN_ON(&decoder_thread_checker_);
+  rtc::CritScope lock(&receive_crit_);
   if (pre_decode_image_callback_) {
     EncodedImage encoded_image(frame->EncodedImage());
     int qp = -1;
@@ -340,20 +291,19 @@
   return Decode(*frame);
 }
 
+void VideoReceiver::DecodingStopped() {
+  // No further calls to Decode() will be made after this point.
+  // TODO(tommi): Make use of this to clarify and check threading model.
+}
+
 int32_t VideoReceiver::RequestKeyFrame() {
-  RTC_DCHECK_RUN_ON(&module_thread_checker_);
-
-  // Since we deregister from the module thread when the decoder thread isn't
-  // running, we should get no calls here if decoding isn't being done.
-  RTC_DCHECK(IsDecoderThreadRunning());
-
   TRACE_EVENT0("webrtc", "RequestKeyFrame");
+  rtc::CritScope cs(&process_crit_);
   if (_frameTypeCallback != nullptr) {
     const int32_t ret = _frameTypeCallback->RequestKeyFrame();
     if (ret < 0) {
       return ret;
     }
-    rtc::CritScope cs(&process_crit_);
     _scheduleKeyRequest = false;
   } else {
     return VCM_MISSING_CALLBACK;
@@ -363,7 +313,6 @@
 
 // Must be called from inside the receive side critical section.
 int32_t VideoReceiver::Decode(const VCMEncodedFrame& frame) {
-  RTC_DCHECK_RUN_ON(&decoder_thread_checker_);
   TRACE_EVENT0("webrtc", "VideoReceiver::Decode");
   // Change decoder if payload type has changed
   VCMGenericDecoder* decoder =
@@ -378,8 +327,11 @@
 int32_t VideoReceiver::RegisterReceiveCodec(const VideoCodec* receiveCodec,
                                             int32_t numberOfCores,
                                             bool requireKeyFrame) {
-  RTC_DCHECK_RUN_ON(&construction_thread_checker_);
-  RTC_DCHECK(!IsDecoderThreadRunning());
+  RTC_DCHECK(construction_thread_.CalledOnValidThread());
+  // TODO(tommi): This method must only be called when the decoder thread
+  // is not running. Do we need a lock? If not, it looks like we might not need
+  // a lock at all for |_codecDataBase|.
+  rtc::CritScope cs(&receive_crit_);
   if (receiveCodec == nullptr) {
     return VCM_PARAMETER_ERROR;
   }
@@ -394,7 +346,6 @@
 int32_t VideoReceiver::IncomingPacket(const uint8_t* incomingPayload,
                                       size_t payloadLength,
                                       const WebRtcRTPHeader& rtpInfo) {
-  RTC_DCHECK_RUN_ON(&module_thread_checker_);
   if (rtpInfo.frameType == kVideoFrameKey) {
     TRACE_EVENT1("webrtc", "VCM::PacketKeyFrame", "seqnum",
                  rtpInfo.header.sequenceNumber);
@@ -426,7 +377,6 @@
 // to sync with audio. Not included in  VideoCodingModule::Delay()
 // Defaults to 0 ms.
 int32_t VideoReceiver::SetMinimumPlayoutDelay(uint32_t minPlayoutDelayMs) {
-  RTC_DCHECK_RUN_ON(&module_thread_checker_);
   _timing->set_min_playout_delay(minPlayoutDelayMs);
   return VCM_OK;
 }
@@ -434,24 +384,22 @@
 // The estimated delay caused by rendering, defaults to
 // kDefaultRenderDelayMs = 10 ms
 int32_t VideoReceiver::SetRenderDelay(uint32_t timeMS) {
-  RTC_DCHECK_RUN_ON(&construction_thread_checker_);
-  RTC_DCHECK(!IsDecoderThreadRunning());
   _timing->set_render_delay(timeMS);
   return VCM_OK;
 }
 
 // Current video delay
 int32_t VideoReceiver::Delay() const {
-  RTC_DCHECK_RUN_ON(&module_thread_checker_);
   return _timing->TargetVideoDelay();
 }
 
-// Only used by VCMRobustnessTest.
 int VideoReceiver::SetReceiverRobustnessMode(
     VideoCodingModule::ReceiverRobustness robustnessMode,
     VCMDecodeErrorMode decode_error_mode) {
-  RTC_DCHECK_RUN_ON(&construction_thread_checker_);
-  RTC_DCHECK(!IsDecoderThreadRunning());
+  RTC_DCHECK(construction_thread_.CalledOnValidThread());
+  // TODO(tommi): This method must only be called when the decoder thread
+  // is not running and we don't need to hold this lock.
+  rtc::CritScope cs(&receive_crit_);
   switch (robustnessMode) {
     case VideoCodingModule::kNone:
       _receiver.SetNackMode(kNoNack, -1, -1);
@@ -469,17 +417,15 @@
 }
 
 void VideoReceiver::SetDecodeErrorMode(VCMDecodeErrorMode decode_error_mode) {
-  RTC_DCHECK_RUN_ON(&construction_thread_checker_);
-  RTC_DCHECK(!IsDecoderThreadRunning());
+  rtc::CritScope cs(&receive_crit_);
   _receiver.SetDecodeErrorMode(decode_error_mode);
 }
 
 void VideoReceiver::SetNackSettings(size_t max_nack_list_size,
                                     int max_packet_age_to_nack,
                                     int max_incomplete_time_ms) {
-  RTC_DCHECK_RUN_ON(&construction_thread_checker_);
-  RTC_DCHECK(!IsDecoderThreadRunning());
   if (max_nack_list_size != 0) {
+    rtc::CritScope cs(&process_crit_);
     max_nack_list_size_ = max_nack_list_size;
   }
   _receiver.SetNackSettings(max_nack_list_size, max_packet_age_to_nack,
@@ -487,22 +433,8 @@
 }
 
 int VideoReceiver::SetMinReceiverDelay(int desired_delay_ms) {
-  RTC_DCHECK_RUN_ON(&construction_thread_checker_);
-  RTC_DCHECK(!IsDecoderThreadRunning());
-  // TODO(tommi): Is the method only used by tests? Maybe could be offered
-  // via a test only subclass?
-  // Info from Stefan: If it is indeed only used by tests I think it's just that
-  // it hasn't been cleaned up when the calling code was cleaned up.
   return _receiver.SetMinReceiverDelay(desired_delay_ms);
 }
 
-bool VideoReceiver::IsDecoderThreadRunning() {
-#if RTC_DCHECK_IS_ON
-  return decoder_thread_is_running_;
-#else
-  return true;
-#endif
-}
-
 }  // namespace vcm
 }  // namespace webrtc
diff --git a/video/video_receive_stream.cc b/video/video_receive_stream.cc
index 2b191f2..9a572ca 100644
--- a/video/video_receive_stream.cc
+++ b/video/video_receive_stream.cc
@@ -226,7 +226,6 @@
   process_thread_->RegisterModule(&video_receiver_, RTC_FROM_HERE);
 
   // Start the decode thread
-  video_receiver_.DecoderThreadStarting();
   decode_thread_.Start();
   rtp_video_stream_receiver_.StartReceive();
 }
@@ -250,7 +249,6 @@
     video_receiver_.TriggerDecoderShutdown();
 
     decode_thread_.Stop();
-    video_receiver_.DecoderThreadStopped();
     // Deregister external decoders so they are no longer running during
     // destruction. This effectively stops the VCM since the decoder thread is
     // stopped, the VCM is deregistered and no asynchronous decoder threads are
@@ -425,6 +423,7 @@
       frame_buffer_->NextFrame(wait_ms, &frame);
 
   if (res == video_coding::FrameBuffer::ReturnReason::kStopped) {
+    video_receiver_.DecodingStopped();
     return false;
   }