Update smoothed bitrate.

webrtc/common_audio/smoothing_filter_unittest.cc

Index: webrtc/common_audio/smoothing_filter_unittest.cc
diff --git a/webrtc/common_audio/smoothing_filter_unittest.cc b/webrtc/common_audio/smoothing_filter_unittest.cc
index c80ffb672cb71b3286e3408d3aaec38fe77b6006..3a6d4260ec595d474668bd747716a96e85adc840 100644
--- a/webrtc/common_audio/smoothing_filter_unittest.cc
+++ b/webrtc/common_audio/smoothing_filter_unittest.cc
@@ -105,4 +105,23 @@ TEST(SmoothingFilterTest, CheckBehaviorAfterInitialized) {
   CheckOutput(&states, kTimeIntervalMs, 1.0, 0.64136f);
 }
 
+TEST(SmoothingFilterTest, CheckBehaviorAfterInitializeConvertToLastSample) {
+  auto states = CreateSmoothingFilter();
+  states.smoothing_filter->AddSample(0.0);
+  states.simulated_clock->AdvanceTimeMilliseconds(100 * kTimeConstantMs);
+  states.smoothing_filter->AddSample(2.0);  // test filter value to 2.
+
+  states.smoothing_filter->AddSample(1.0);
+  auto output = states.smoothing_filter->GetAverage();
+  EXPECT_TRUE(output);
+  EXPECT_NEAR(2, *output, kMaxAbsError);
+  states.simulated_clock->AdvanceTimeMilliseconds(kTimeConstantMs);
+  output = states.smoothing_filter->GetAverage();
+  EXPECT_TRUE(output);
+  EXPECT_NEAR(1.36787f, *output, kMaxAbsError);
+  states.simulated_clock->AdvanceTimeMilliseconds(kTimeConstantMs);
+  output = states.smoothing_filter->GetAverage();
+  EXPECT_TRUE(output);
+  EXPECT_NEAR(1.13533f, *output, kMaxAbsError);
+}
 }  // namespace webrtc