Revert of Remove ignored return code from modules.

webrtc/modules/remote_bitrate_estimator/test/bwe.cc

Index: webrtc/modules/remote_bitrate_estimator/test/bwe.cc
diff --git a/webrtc/modules/remote_bitrate_estimator/test/bwe.cc b/webrtc/modules/remote_bitrate_estimator/test/bwe.cc
index 5e282c6f087466628d542ab79c7bb0beebf9ed11..c667b6864e4638a40e3d227849f6230dab8d8930 100644
--- a/webrtc/modules/remote_bitrate_estimator/test/bwe.cc
+++ b/webrtc/modules/remote_bitrate_estimator/test/bwe.cc
@@ -67,7 +67,7 @@
   int64_t TimeUntilNextProcess() override {
     return std::numeric_limits<int64_t>::max();
   }
-  void Process() override {}
+  int Process() override { return 0; }
 
  private:
   RTC_DISALLOW_COPY_AND_ASSIGN(NullBweSender);