Set min BWE bitrate form 10kbps to 5kbps and centralize minimum bitrate.

webrtc/modules/remote_bitrate_estimator/bwe_defines.cc

Index: webrtc/modules/remote_bitrate_estimator/bwe_defines.cc
diff --git a/webrtc/modules/remote_bitrate_estimator/bwe_defines.cc b/webrtc/modules/remote_bitrate_estimator/bwe_defines.cc
index 3587ebf744b9925525f0e08bab3fb75a200799ff..69769f035bb011229faf4ae717641b41d4349931 100644
--- a/webrtc/modules/remote_bitrate_estimator/bwe_defines.cc
+++ b/webrtc/modules/remote_bitrate_estimator/bwe_defines.cc
@@ -7,7 +7,23 @@
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
+
+#include "webrtc/system_wrappers/include/field_trial.h"
+
 namespace webrtc {
 
 const char* kBweTypeHistogram = "WebRTC.BWE.Types";
+
+namespace congestion_controller {
+int GetMinBitrateBps() {
+  constexpr int kAudioMinBitrateBps = 5000;
+  constexpr int kMinBitrateBps = 10000;
+  if (webrtc::field_trial::FindFullName("WebRTC-Audio-SendSideBwe") ==
+      "Enabled") {
+    return kAudioMinBitrateBps;
+  }
+  return kMinBitrateBps;
+}
+
+}  // namespace congestion_controller
 }  // namespace webrtc