Fix BitrateControllerImpl not to ignore BW probe results mid-call.

Previously when BitrateControllerImpl::OnDelayBasedBweResult() is
called as result of a probe it was calling
bandwidth_estimation_.SetSendBitrate(), but not
UpdateDelayBasedEstimate(). As result SendSideBandwidthEstimation was
effectively ignoring probe results as it kept the old
delay_based_bitrate_bps_ value, which caps the resulting bitrate.

BUG=webrtc:6332,webrtc:6710

Review-Url: https://codereview.webrtc.org/2481383002
Cr-Commit-Position: refs/heads/master@{#15071}
diff --git a/webrtc/modules/bitrate_controller/bitrate_controller_impl.cc b/webrtc/modules/bitrate_controller/bitrate_controller_impl.cc
index a33d97e..be0e0f1 100644
--- a/webrtc/modules/bitrate_controller/bitrate_controller_impl.cc
+++ b/webrtc/modules/bitrate_controller/bitrate_controller_impl.cc
@@ -189,11 +189,10 @@
     return;
   {
     rtc::CritScope cs(&critsect_);
+    bandwidth_estimation_.UpdateDelayBasedEstimate(clock_->TimeInMilliseconds(),
+                                                   result.target_bitrate_bps);
     if (result.probe) {
       bandwidth_estimation_.SetSendBitrate(result.target_bitrate_bps);
-    } else {
-      bandwidth_estimation_.UpdateDelayBasedEstimate(
-          clock_->TimeInMilliseconds(), result.target_bitrate_bps);
     }
   }
   MaybeTriggerOnNetworkChanged();