Fix race / crash in OnNetworkRouteChanged().

To achieve this some refactoring was done to make it possible to synchronize
access to the DelayBasedBwe in TransportFeedbackAdapter:
- The callback was removed from DelayBasedBwe, it now instead returns its
  result.
- TransportFeedbackAdapter was moved to modules/congestion_controller to avoid
  unnecessary dependencies.

Reenables previously disabled flaky test. Can no longer reproduce flakiness with gtest-parallel and asan/tsan builds.

BUG=webrtc:6427, webrtc:6422

Review-Url: https://codereview.webrtc.org/2366333003
Cr-Commit-Position: refs/heads/master@{#14430}

webrtc/modules/bitrate_controller/include/bitrate_controller.h

@@ -17,9 +17,9 @@
 
 #include <map>
 
+#include "webrtc/modules/congestion_controller/delay_based_bwe.h"
 #include "webrtc/modules/include/module.h"
 #include "webrtc/modules/pacing/paced_sender.h"
-#include "webrtc/modules/remote_bitrate_estimator/include/remote_bitrate_estimator.h"
 #include "webrtc/modules/rtp_rtcp/include/rtp_rtcp_defines.h"
 
 namespace webrtc {
@@ -44,7 +44,7 @@ class BitrateObserver {
   virtual ~BitrateObserver() {}
 };
 
-class BitrateController : public Module, public RemoteBitrateObserver {
+class BitrateController : public Module {
   // This class collects feedback from all streams sent to a peer (via
   // RTCPBandwidthObservers). It does one  aggregated send side bandwidth
   // estimation and divide the available bitrate between all its registered
@@ -78,6 +78,8 @@ class BitrateController : public Module, public RemoteBitrateObserver {
                              int min_bitrate_bps,
                              int max_bitrate_bps) = 0;
 
+  virtual void OnDelayBasedBweResult(const DelayBasedBwe::Result& result) = 0;
+
   // Gets the available payload bandwidth in bits per second. Note that
   // this bandwidth excludes packet headers.
   virtual bool AvailableBandwidth(uint32_t* bandwidth) const = 0;