Revert of Remove ignored return code from modules.

webrtc/modules/rtp_rtcp/source/receive_statistics_impl.cc

Index: webrtc/modules/rtp_rtcp/source/receive_statistics_impl.cc
diff --git a/webrtc/modules/rtp_rtcp/source/receive_statistics_impl.cc b/webrtc/modules/rtp_rtcp/source/receive_statistics_impl.cc
index 022fc9610f45bb706702aea603321435850542e2..24f1e2c96ed8c10acf1dc5ebf97b7fb7926a8087 100644
--- a/webrtc/modules/rtp_rtcp/source/receive_statistics_impl.cc
+++ b/webrtc/modules/rtp_rtcp/source/receive_statistics_impl.cc
@@ -454,13 +454,14 @@
   }
 }
 
-void ReceiveStatisticsImpl::Process() {
+int32_t ReceiveStatisticsImpl::Process() {
   CriticalSectionScoped cs(receive_statistics_lock_.get());
   for (StatisticianImplMap::iterator it = statisticians_.begin();
        it != statisticians_.end(); ++it) {
     it->second->ProcessBitrate();
   }
   last_rate_update_ms_ = clock_->TimeInMilliseconds();
+  return 0;
 }
 
 int64_t ReceiveStatisticsImpl::TimeUntilNextProcess() {
@@ -529,7 +530,7 @@
 
 int64_t NullReceiveStatistics::TimeUntilNextProcess() { return 0; }
 
-void NullReceiveStatistics::Process() {}
+int32_t NullReceiveStatistics::Process() { return 0; }
 
 void NullReceiveStatistics::RegisterRtcpStatisticsCallback(
     RtcpStatisticsCallback* callback) {}