Probing: Add support for exponential startup probing

webrtc/modules/remote_bitrate_estimator/aimd_rate_control.h

Index: webrtc/modules/remote_bitrate_estimator/aimd_rate_control.h
diff --git a/webrtc/modules/remote_bitrate_estimator/aimd_rate_control.h b/webrtc/modules/remote_bitrate_estimator/aimd_rate_control.h
index 2b2e85bf911b0b16b80f092f78919a3b31c964c3..68137945ffbde4a4db2e643d81df95ad34a1a6dc 100644
--- a/webrtc/modules/remote_bitrate_estimator/aimd_rate_control.h
+++ b/webrtc/modules/remote_bitrate_estimator/aimd_rate_control.h
@@ -51,8 +51,8 @@ class AimdRateControl {
   // in the "decrease" state the bitrate will be decreased to slightly below the
   // incoming bitrate. When in the "hold" state the bitrate will be kept
   // constant to allow built up queues to drain.
-  uint32_t ChangeBitrate(uint32_t current_bit_rate,
-                         uint32_t incoming_bit_rate,
+  uint32_t ChangeBitrate(int current_bit_rate,
+                         int incoming_bit_rate,
                          int64_t now_ms);
   uint32_t MultiplicativeRateIncrease(int64_t now_ms, int64_t last_ms,
                                       uint32_t current_bitrate_bps) const;
@@ -64,9 +64,9 @@ class AimdRateControl {
   void ChangeState(RateControlState new_state);
   void ChangeRegion(RateControlRegion region);
 
-  uint32_t min_configured_bitrate_bps_;
-  uint32_t max_configured_bitrate_bps_;
-  uint32_t current_bitrate_bps_;
+  int min_configured_bitrate_bps_;
+  int max_configured_bitrate_bps_;
+  int current_bitrate_bps_;
   float avg_max_bitrate_kbps_;
   float var_max_bitrate_kbps_;
   RateControlState rate_control_state_;