Reland of move ignored return code from modules. (patchset #1 id:1 of https://codereview.webrtc.org/1736663004/ )

Reason for revert:
Revert breaks other uses, a fix will be rolled into Chromium instead.

Original issue's description:
> Revert of Remove ignored return code from modules. (patchset #3 id:40001 of https://codereview.webrtc.org/1703833002/ )
>
> Reason for revert:
> Breaks Chromium.
>
> Original issue's description:
> > Remove ignored return code from modules.
> >
> > ModuleProcessImpl doesn't act on return codes and having them around is
> > confusing (it's unclear what an error return code here would do even).
> >
> > BUG=
> > R=tommi@webrtc.org
> >
> > Committed: https://chromium.googlesource.com/external/webrtc/+/f14c47a58cb2a333cb9b11aef593f0e632fdb28a
>
> TBR=tommi@webrtc.org,pbos@webrtc.org
> # Skipping CQ checks because original CL landed less than 1 days ago.
> NOPRESUBMIT=true
> NOTREECHECKS=true
> NOTRY=true
> BUG=
>
> Committed: https://crrev.com/da33a8a2a22f6d19ba2a8cce963beafbdbaa8fd8
> Cr-Commit-Position: refs/heads/master@{#11761}

TBR=tommi@webrtc.org,torbjorng@webrtc.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=

Review URL: https://codereview.webrtc.org/1737013002

Cr-Commit-Position: refs/heads/master@{#11762}
diff --git a/webrtc/modules/video_coding/video_receiver.cc b/webrtc/modules/video_coding/video_receiver.cc
index 02d51a7..e7844d0 100644
--- a/webrtc/modules/video_coding/video_receiver.cc
+++ b/webrtc/modules/video_coding/video_receiver.cc
@@ -63,9 +63,7 @@
 #endif
 }
 
-int32_t VideoReceiver::Process() {
-  int32_t returnValue = VCM_OK;
-
+void VideoReceiver::Process() {
   // Receive-side statistics
   if (_receiveStatsTimer.TimeUntilProcess() == 0) {
     _receiveStatsTimer.Processed();
@@ -108,12 +106,8 @@
       CriticalSectionScoped cs(process_crit_sect_.get());
       request_key_frame = _scheduleKeyRequest && _frameTypeCallback != NULL;
     }
-    if (request_key_frame) {
-      const int32_t ret = RequestKeyFrame();
-      if (ret != VCM_OK && returnValue == VCM_OK) {
-        returnValue = ret;
-      }
-    }
+    if (request_key_frame)
+      RequestKeyFrame();
   }
 
   // Packet retransmission requests
@@ -135,9 +129,6 @@
       int32_t ret = VCM_OK;
       if (request_key_frame) {
         ret = RequestKeyFrame();
-        if (ret != VCM_OK && returnValue == VCM_OK) {
-          returnValue = ret;
-        }
       }
       if (ret == VCM_OK && !nackList.empty()) {
         CriticalSectionScoped cs(process_crit_sect_.get());
@@ -147,8 +138,6 @@
       }
     }
   }
-
-  return returnValue;
 }
 
 int64_t VideoReceiver::TimeUntilNextProcess() {