Fix Bug: Video with Variable Frame Rate plays at incorrect speed.

media/base/moving_average_unittest.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/time/time.h"
 #include "media/base/moving_average.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace media {
 
-TEST(MovingAverageTest, Average) {
+TEST(MovingAverageTest, AverageAndDeviation) {
   const int kSamples = 5;
   MovingAverage moving_average(kSamples);
   moving_average.AddSample(base::TimeDelta::FromSeconds(1));
   EXPECT_EQ(base::TimeDelta::FromSeconds(1), moving_average.Average());
+  EXPECT_EQ(base::TimeDelta(), moving_average.Deviation());
+
   for (int i = 0; i < kSamples - 1; ++i)
     moving_average.AddSample(base::TimeDelta::FromSeconds(1));
   EXPECT_EQ(base::TimeDelta::FromSeconds(1), moving_average.Average());
+  EXPECT_EQ(base::TimeDelta(), moving_average.Deviation());
 
+  base::TimeDelta expect_deviation[] = {
+      base::TimeDelta::FromMicroseconds(200000),
+      base::TimeDelta::FromMicroseconds(244948),
+      base::TimeDelta::FromMicroseconds(244948),
+      base::TimeDelta::FromMicroseconds(200000),
+      base::TimeDelta::FromMilliseconds(0),
+  };
   for (int i = 0; i < kSamples; ++i) {
     moving_average.AddSample(base::TimeDelta::FromMilliseconds(500));
     EXPECT_EQ(base::TimeDelta::FromMilliseconds(1000 - (i + 1) * 100),
               moving_average.Average());
+    EXPECT_EQ(expect_deviation[i], moving_average.Deviation());
   }
 }
 
 TEST(MovingAverageTest, Reset) {
   MovingAverage moving_average(2);
   moving_average.AddSample(base::TimeDelta::FromSeconds(1));
   EXPECT_EQ(base::TimeDelta::FromSeconds(1), moving_average.Average());
   moving_average.Reset();
   moving_average.AddSample(base::TimeDelta());
   EXPECT_EQ(base::TimeDelta(), moving_average.Average());
+  EXPECT_EQ(base::TimeDelta(), moving_average.Deviation());
 }
 
 }  // namespace media