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

BUG=webrtc:6522

Review-Url: https://codereview.webrtc.org/2415543002
Cr-Commit-Position: refs/heads/master@{#14947}
diff --git a/webrtc/modules/bitrate_controller/bitrate_controller_unittest.cc b/webrtc/modules/bitrate_controller/bitrate_controller_unittest.cc
index 56bb41e..6f6c57d 100644
--- a/webrtc/modules/bitrate_controller/bitrate_controller_unittest.cc
+++ b/webrtc/modules/bitrate_controller/bitrate_controller_unittest.cc
@@ -14,7 +14,7 @@
 #include "webrtc/logging/rtc_event_log/mock/mock_rtc_event_log.h"
 #include "webrtc/modules/bitrate_controller/include/bitrate_controller.h"
 #include "webrtc/modules/pacing/mock/mock_paced_sender.h"
-#include "webrtc/modules/rtp_rtcp/include/rtp_rtcp_defines.h"
+#include "webrtc/modules/remote_bitrate_estimator/include/bwe_defines.h"
 #include "webrtc/test/field_trial.h"
 #include "webrtc/test/gtest.h"
 
@@ -98,7 +98,8 @@
   controller_->SetMinMaxBitrate(0, 0);
   EXPECT_EQ(kStartBitrateBps, bitrate_observer_.last_bitrate_);
   bandwidth_observer_->OnReceivedEstimatedBitrate(kDefaultMinBitrateBps / 2);
-  EXPECT_EQ(kDefaultMinBitrateBps, bitrate_observer_.last_bitrate_);
+  EXPECT_EQ(webrtc::congestion_controller::GetMinBitrateBps(),
+            bitrate_observer_.last_bitrate_);
   bandwidth_observer_->OnReceivedEstimatedBitrate(2 * kDefaultMaxBitrateBps);
   clock_.AdvanceTimeMilliseconds(1000);
   controller_->Process();