Reland of "Revert of Update the BWE when the network route changes. (patchset #5 id:180001 of https://… (patchset #1 id:1 of https://codereview.webrtc.org/2098703004/ )

Reason for revert:
It turns out this revert was not necessary because the connection-state mapping for turn-turn connections was not done in connection.

Original issue's description:
> Revert of Revert "Revert of Update the BWE when the network route changes. (patchset #5 id:180001 of https://… (patchset #5 id:120001 of https://codereview.webrtc.org/2041593002/ )
>
> Reason for revert:
> ReadyToSendMedia did not consider the new presumed_writable state.
>
> Original issue's description:
> > Revert "Revert of Update the BWE when the network route changes. (patchset #5 id:180001 of https://codereview.webrtc.org/2000063003/ )"
> >
> > This reverts commit 72d41aa6da94dacb8a8464d1abd4ca7d1afffc65.
> >
> > New change made:
> > Do not reset the BWE when the new network route is not ready to send media.
> >
> > BUG=
> > R=pthatcher@webrtc.org, stefan@webrtc.org
> >

TBR=pthatcher@webrtc.org,stefan@webrtc.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=

Review-Url: https://codereview.webrtc.org/2094863003
Cr-Commit-Position: refs/heads/master@{#13282}
diff --git a/webrtc/modules/bitrate_controller/bitrate_controller_impl.cc b/webrtc/modules/bitrate_controller/bitrate_controller_impl.cc
index 09652d8..c99bd53 100644
--- a/webrtc/modules/bitrate_controller/bitrate_controller_impl.cc
+++ b/webrtc/modules/bitrate_controller/bitrate_controller_impl.cc
@@ -138,6 +138,18 @@
   MaybeTriggerOnNetworkChanged();
 }
 
+void BitrateControllerImpl::ResetBitrates(int bitrate_bps,
+                                          int min_bitrate_bps,
+                                          int max_bitrate_bps) {
+  {
+    rtc::CritScope cs(&critsect_);
+    bandwidth_estimation_ = SendSideBandwidthEstimation();
+    bandwidth_estimation_.SetBitrates(bitrate_bps, min_bitrate_bps,
+                                      max_bitrate_bps);
+  }
+  MaybeTriggerOnNetworkChanged();
+}
+
 void BitrateControllerImpl::SetReservedBitrate(uint32_t reserved_bitrate_bps) {
   {
     rtc::CritScope cs(&critsect_);