Pause/resume pacer from Call instead of via SendStreams.

BUG=webrtc:5073

Review URL: https://codereview.webrtc.org/1398443007

Cr-Commit-Position: refs/heads/master@{#10271}

webrtc/call/call.cc

@@ -396,6 +396,7 @@ void Call::SignalNetworkState(NetworkState state) {
   // to guarantee a consistent state across streams.
   rtc::CritScope lock(&network_enabled_crit_);
   network_enabled_ = state == kNetworkUp;
+  channel_group_->SignalNetworkState(state);
   {
     ReadLockScoped write_lock(*send_crit_);
     for (auto& kv : video_send_ssrcs_) {

webrtc/video_engine/vie_channel_group.cc

@@ -422,6 +422,14 @@ void ChannelGroup::SetChannelRembStatus(bool sender,
   }
 }
 
+void ChannelGroup::SignalNetworkState(NetworkState state) {
+  if (state == kNetworkUp) {
+    pacer_->Resume();
+  } else {
+    pacer_->Pause();
+  }
+}
+
 void ChannelGroup::OnNetworkChanged(uint32_t target_bitrate_bps,
                                     uint8_t fraction_loss,
                                     int64_t rtt) {

webrtc/video_engine/vie_channel_group.h

@@ -69,6 +69,8 @@ class ChannelGroup : public BitrateObserver {
 
   void SetChannelRembStatus(bool sender, bool receiver, ViEChannel* channel);
 
+  void SignalNetworkState(NetworkState state);
+
   BitrateController* GetBitrateController() const;
   CallStats* GetCallStats() const;
   RemoteBitrateEstimator* GetRemoteBitrateEstimator() const;

webrtc/video_engine/vie_encoder.cc

@@ -185,11 +185,6 @@ void ViEEncoder::SetNetworkTransmissionState(bool is_transmitting) {
     CriticalSectionScoped cs(data_cs_.get());
     network_is_transmitting_ = is_transmitting;
   }
-  if (is_transmitting) {
-    pacer_->Resume();
-  } else {
-    pacer_->Pause();
-  }
 }
 
 void ViEEncoder::Pause() {