Introduce AudioClock to improve playback delay calculations.

media/filters/buffered_audio_tracker_unittest.cc

Index: media/filters/buffered_audio_tracker_unittest.cc
diff --git a/media/filters/buffered_audio_tracker_unittest.cc b/media/filters/buffered_audio_tracker_unittest.cc
new file mode 100644
index 0000000000000000000000000000000000000000..0a0462c71b1133fd503e7eea6608c0ef06598bc0
--- /dev/null
+++ b/media/filters/buffered_audio_tracker_unittest.cc
@@ -0,0 +1,68 @@
+// Copyright 2014 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 "media/filters/buffered_audio_tracker.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace media {
+
+class BufferedAudioTrackerTest : public testing::Test {
+ public:
+  BufferedAudioTrackerTest() : tracker_(2000) {}
+  virtual ~BufferedAudioTrackerTest() {}
+
+  int BufferedTimeInMilliseconds() {
+    return tracker_.BufferedTime().InMilliseconds();
+  }
+
+  BufferedAudioTracker tracker_;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(BufferedAudioTrackerTest);
+};
+
+TEST_F(BufferedAudioTrackerTest, BufferedTimeStartsAtZero) {
+  EXPECT_EQ(0, BufferedTimeInMilliseconds());
+}
+
+TEST_F(BufferedAudioTrackerTest, BufferedTimeRemainsAtZeroAfterCallback) {
+  tracker_.AudioCallbackFired(200);
+  EXPECT_EQ(0, BufferedTimeInMilliseconds());
+}
+
+TEST_F(BufferedAudioTrackerTest, BufferedTimeMatchesWrittenData) {
+  tracker_.WroteAudio(100, 1.0);
+  EXPECT_EQ(50, BufferedTimeInMilliseconds());
+
+  tracker_.WroteAudio(100, 1.0);
+  EXPECT_EQ(100, BufferedTimeInMilliseconds());
+
+  tracker_.WroteAudio(100, 2.0);
+  EXPECT_EQ(200, BufferedTimeInMilliseconds());
+
+  tracker_.WroteAudio(100, 2.0);
+  EXPECT_EQ(300, BufferedTimeInMilliseconds());
+
+  tracker_.WroteAudio(100, 0.5);
+  EXPECT_EQ(325, BufferedTimeInMilliseconds());
+
+  tracker_.WroteAudio(100, 0.5);
+  EXPECT_EQ(350, BufferedTimeInMilliseconds());
+}
+
+TEST_F(BufferedAudioTrackerTest, AudioCallbackTrimsBufferedTime) {
+  tracker_.WroteAudio(100, 1.0);
+  EXPECT_EQ(50, BufferedTimeInMilliseconds());
+
+  tracker_.AudioCallbackFired(80);
+  EXPECT_EQ(40, BufferedTimeInMilliseconds());
+
+  tracker_.AudioCallbackFired(40);
+  EXPECT_EQ(20, BufferedTimeInMilliseconds());
+
+  tracker_.AudioCallbackFired(0);
+  EXPECT_EQ(0, BufferedTimeInMilliseconds());
+}
+
+}  // namespace media