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

webrtc/modules/congestion_controller/include/defines.h

Index: webrtc/modules/congestion_controller/include/defines.h
diff --git a/webrtc/modules/audio_coding/neteq/packet.cc b/webrtc/modules/congestion_controller/include/defines.h
similarity index 60%
copy from webrtc/modules/audio_coding/neteq/packet.cc
copy to webrtc/modules/congestion_controller/include/defines.h
index 8a19fe4d5923d5e22a5b485600c6da0c5f3856ba..001b1e414eed9b5bb33dd0f8644b4e39b403877a 100644
--- a/webrtc/modules/audio_coding/neteq/packet.cc
+++ b/webrtc/modules/congestion_controller/include/defines.h
@@ -8,12 +8,13 @@
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
-#include "webrtc/modules/audio_coding/neteq/packet.h"
+#ifndef WEBRTC_MODULES_CONGESTION_CONTROLLER_INCLUDE_DEFINES_H_
+#define WEBRTC_MODULES_CONGESTION_CONTROLLER_INCLUDE_DEFINES_H_
 
 namespace webrtc {
-
-Packet::Packet() = default;
-
-Packet::~Packet() = default;
-
+namespace congestion_controller {
+constexpr int kMinBitrateBps = 5000;
+}  // namespace congestion_controller
 }  // namespace webrtc
+
+#endif  // WEBRTC_MODULES_CONGESTION_CONTROLLER_INCLUDE_DEFINES_H_