ModuleRtcRtcpImpl2: remove Module inheritance.

This change achieves an Idle Wakeup savings of 200 Hz.

ModuleRtcRtcpImpl2 had Process() logic only active if TMMBR() is
enabled in RtcpSender, which it never is. Hence the Module
inheritance could be removed. The change removes all known
dependencies of the module inheritance, and any related mentions
of ProcessThread.

Fixed: webrtc:11581
Change-Id: I440942f07187fdb9ac18186dab088633969b340e
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/222604
Reviewed-by: Tommi <tommi@webrtc.org>
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Commit-Queue: Markus Handell <handellm@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#34358}
diff --git a/video/rtp_video_stream_receiver2_unittest.cc b/video/rtp_video_stream_receiver2_unittest.cc
index d23b604..7ccf0a5 100644
--- a/video/rtp_video_stream_receiver2_unittest.cc
+++ b/video/rtp_video_stream_receiver2_unittest.cc
@@ -166,16 +166,14 @@
             TaskQueueFactory::Priority::NORMAL)),
         task_queue_setter_(task_queue_.get()),
         override_field_trials_(field_trials),
-        config_(CreateConfig()),
-        process_thread_(ProcessThread::Create("TestThread")) {
+        config_(CreateConfig()) {
     rtp_receive_statistics_ =
         ReceiveStatistics::Create(Clock::GetRealTimeClock());
     rtp_video_stream_receiver_ = std::make_unique<RtpVideoStreamReceiver2>(
         TaskQueueBase::Current(), Clock::GetRealTimeClock(), &mock_transport_,
         nullptr, nullptr, &config_, rtp_receive_statistics_.get(), nullptr,
-        nullptr, process_thread_.get(), &mock_nack_sender_,
-        &mock_key_frame_request_sender_, &mock_on_complete_frame_callback_,
-        nullptr, nullptr);
+        nullptr, &mock_nack_sender_, &mock_key_frame_request_sender_,
+        &mock_on_complete_frame_callback_, nullptr, nullptr);
     VideoCodec codec;
     codec.codecType = kVideoCodecGeneric;
     rtp_video_stream_receiver_->AddReceiveCodec(kPayloadType, codec, {},
@@ -250,7 +248,6 @@
   MockKeyFrameRequestSender mock_key_frame_request_sender_;
   MockTransport mock_transport_;
   MockOnCompleteFrameCallback mock_on_complete_frame_callback_;
-  std::unique_ptr<ProcessThread> process_thread_;
   std::unique_ptr<ReceiveStatistics> rtp_receive_statistics_;
   std::unique_ptr<RtpVideoStreamReceiver2> rtp_video_stream_receiver_;
   RtpPacketSinkInterface* test_packet_sink_ = nullptr;
@@ -1135,8 +1132,8 @@
   auto receiver = std::make_unique<RtpVideoStreamReceiver2>(
       TaskQueueBase::Current(), Clock::GetRealTimeClock(), &mock_transport_,
       nullptr, nullptr, &config_, rtp_receive_statistics_.get(), nullptr,
-      nullptr, process_thread_.get(), &mock_nack_sender_, nullptr,
-      &mock_on_complete_frame_callback_, nullptr, mock_frame_transformer);
+      nullptr, &mock_nack_sender_, nullptr, &mock_on_complete_frame_callback_,
+      nullptr, mock_frame_transformer);
   VideoCodec video_codec;
   video_codec.codecType = kVideoCodecGeneric;
   receiver->AddReceiveCodec(kPayloadType, video_codec, {},