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

webrtc/modules/congestion_controller/congestion_controller_unittest.cc

Index: webrtc/modules/congestion_controller/congestion_controller_unittest.cc
diff --git a/webrtc/modules/congestion_controller/congestion_controller_unittest.cc b/webrtc/modules/congestion_controller/congestion_controller_unittest.cc
index e840294d9f09a96da12b5631606ab717c2227e16..06d17d5667a36593378bb2d52a6f8edd97e9e881 100644
--- a/webrtc/modules/congestion_controller/congestion_controller_unittest.cc
+++ b/webrtc/modules/congestion_controller/congestion_controller_unittest.cc
@@ -135,10 +135,11 @@ TEST_F(CongestionControllerTest, ResetBweAndBitrates) {
   controller_->ResetBweAndBitrates(new_bitrate, -1, -1);
 
   // If the bitrate is reset to -1, the new starting bitrate will be
-  // the minimum default bitrate 10000bps.
-  int min_default_bitrate = 10000;
-  EXPECT_CALL(observer_, OnNetworkChanged(min_default_bitrate, _, _));
-  EXPECT_CALL(*pacer_, SetEstimatedBitrate(min_default_bitrate));
+  // the minimum default bitrate kMinBitrateBps.
+  EXPECT_CALL(observer_, OnNetworkChanged(
+                             CongestionController::GetMinBitrateBps(), _, _));
+  EXPECT_CALL(*pacer_,
+              SetEstimatedBitrate(CongestionController::GetMinBitrateBps()));
   controller_->ResetBweAndBitrates(-1, -1, -1);
 }