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

webrtc/modules/congestion_controller/congestion_controller.cc

Index: webrtc/modules/congestion_controller/congestion_controller.cc
diff --git a/webrtc/modules/congestion_controller/congestion_controller.cc b/webrtc/modules/congestion_controller/congestion_controller.cc
index f7e7e5625a2984500bbb8a8231935181c3f42dc5..de73a696732a87a67729dc4d31ac7e52dfcd2d8f 100644
--- a/webrtc/modules/congestion_controller/congestion_controller.cc
+++ b/webrtc/modules/congestion_controller/congestion_controller.cc
@@ -27,6 +27,7 @@
 #include "webrtc/modules/remote_bitrate_estimator/remote_bitrate_estimator_single_stream.h"
 #include "webrtc/modules/utility/include/process_thread.h"
 #include "webrtc/system_wrappers/include/critical_section_wrapper.h"
+#include "webrtc/system_wrappers/include/field_trial.h"
 #include "webrtc/video/payload_router.h"
 
 namespace webrtc {
@@ -42,9 +43,8 @@ static void ClampBitrates(int* bitrate_bps,
   // TODO(holmer): We should make sure the default bitrates are set to 10 kbps,
   // and that we don't try to set the min bitrate to 0 from any applications.
   // The congestion controller should allow a min bitrate of 0.
-  const int kMinBitrateBps = 10000;
-  if (*min_bitrate_bps < kMinBitrateBps)
-    *min_bitrate_bps = kMinBitrateBps;
+  if (*min_bitrate_bps < CongestionController::GetMinBitrateBps())
+    *min_bitrate_bps = CongestionController::GetMinBitrateBps();
   if (*max_bitrate_bps > 0)
     *max_bitrate_bps = std::max(*min_bitrate_bps, *max_bitrate_bps);
   if (*bitrate_bps > 0)
@@ -60,7 +60,7 @@ class WrappingBitrateEstimator : public RemoteBitrateEstimator {
         rbe_(new RemoteBitrateEstimatorSingleStream(observer_, clock_)),
         using_absolute_send_time_(false),
         packets_since_absolute_send_time_(0),
-        min_bitrate_bps_(RemoteBitrateEstimator::kDefaultMinBitrateBps) {}
+        min_bitrate_bps_(CongestionController::GetMinBitrateBps()) {}
 
   virtual ~WrappingBitrateEstimator() {}
 
@@ -153,6 +153,16 @@ class WrappingBitrateEstimator : public RemoteBitrateEstimator {
 
 }  // namespace
 
+
+int CongestionController::GetMinBitrateBps() {
+  constexpr int kAudioMinBitrateBps = 5000;
+  constexpr int kMinBitrateBps = 10000;
+  if (webrtc::field_trial::FindFullName("WebRTC-Audio-SendSideBwe") ==
+      "Enabled")

[stefan-webrtc, 2016/11/01 09:09:15]

{} since it's a multi-line if

[michaelt, 2016/11/01 09:21:55]

Done.

+    return kAudioMinBitrateBps;
+  return kMinBitrateBps;
+}
+
 CongestionController::CongestionController(
     Clock* clock,
     Observer* observer,
@@ -171,7 +181,7 @@ CongestionController::CongestionController(
           new RateLimiter(clock, kRetransmitWindowSizeMs)),
       remote_estimator_proxy_(clock_, packet_router_.get()),
       transport_feedback_adapter_(clock_, bitrate_controller_.get()),
-      min_bitrate_bps_(RemoteBitrateEstimator::kDefaultMinBitrateBps),
+      min_bitrate_bps_(GetMinBitrateBps()),
       max_bitrate_bps_(0),
       last_reported_bitrate_bps_(0),
       last_reported_fraction_loss_(0),
@@ -202,7 +212,7 @@ CongestionController::CongestionController(
           new RateLimiter(clock, kRetransmitWindowSizeMs)),
       remote_estimator_proxy_(clock_, packet_router_.get()),
       transport_feedback_adapter_(clock_, bitrate_controller_.get()),
-      min_bitrate_bps_(RemoteBitrateEstimator::kDefaultMinBitrateBps),
+      min_bitrate_bps_(GetMinBitrateBps()),
       max_bitrate_bps_(0),
       last_reported_bitrate_bps_(0),
       last_reported_fraction_loss_(0),