fix wrong implementation of AimdRateControl::TimeToReduceFurther.

webrtc/modules/remote_bitrate_estimator/aimd_rate_control_unittest.cc

Index: webrtc/modules/remote_bitrate_estimator/aimd_rate_control_unittest.cc
diff --git a/webrtc/modules/remote_bitrate_estimator/aimd_rate_control_unittest.cc b/webrtc/modules/remote_bitrate_estimator/aimd_rate_control_unittest.cc
index b36b16ddbf1d137d025e2a8a1886a950399ef753..2bb4bf68c59ad6f4a6fae933c0b49cbc33e7df0b 100644
--- a/webrtc/modules/remote_bitrate_estimator/aimd_rate_control_unittest.cc
+++ b/webrtc/modules/remote_bitrate_estimator/aimd_rate_control_unittest.cc
@@ -89,4 +89,36 @@ TEST(AimdRateControlTest, GetLastBitrateDecrease) {
             states.aimd_rate_control->GetLastBitrateDecreaseBps());
 }
 
+TEST(AimdRateControlTest, OneRTTWithoutBitrateChangeWhenOverUsing) {
+  auto states = CreateAimdRateControlStates();
+  constexpr int kBitrate = 300000;
+  constexpr int64_t kRtt = 150;
+  InitBitrate(states, kBitrate, states.simulated_clock->TimeInMilliseconds());
+  UpdateRateControl(states, kBwOverusing, kBitrate - 2000,
+                    states.simulated_clock->TimeInMilliseconds());
+  states.aimd_rate_control->SetRtt(kRtt);
+  EXPECT_FALSE(states.aimd_rate_control->TimeToReduceFurther(
+               states.simulated_clock->TimeInMilliseconds(), kBitrate));
+  states.simulated_clock->AdvanceTimeMilliseconds(kRtt);
+  EXPECT_TRUE(states.aimd_rate_control->TimeToReduceFurther(
+              states.simulated_clock->TimeInMilliseconds(), kBitrate));
+}
+
+TEST(AimdRateControlTest, EstimatedAlreadyAchievedWhenOverUsing) {
+  auto states = CreateAimdRateControlStates();
+  constexpr int kBitrate = 300000;
+  constexpr int64_t kRtt = 150;
+  uint32_t bitrate;
+  InitBitrate(states, kBitrate, states.simulated_clock->TimeInMilliseconds());
+  UpdateRateControl(states, kBwOverusing, kBitrate - 2000,
+                    states.simulated_clock->TimeInMilliseconds());
+  states.aimd_rate_control->SetRtt(kRtt);
+  bitrate = states.aimd_rate_control->LatestEstimate();
+  EXPECT_FALSE(states.aimd_rate_control->TimeToReduceFurther(
+               states.simulated_clock->TimeInMilliseconds(), bitrate));
+  bitrate = static_cast<uint32_t>(0.95 * bitrate);
+  EXPECT_TRUE(states.aimd_rate_control->TimeToReduceFurther(
+              states.simulated_clock->TimeInMilliseconds(), bitrate));
+}
+
 }  // namespace webrtc