Add gapless playback support for AAC playback.

media/filters/chunk_demuxer_unittest.cc

Index: media/filters/chunk_demuxer_unittest.cc
diff --git a/media/filters/chunk_demuxer_unittest.cc b/media/filters/chunk_demuxer_unittest.cc
index 3bca45f646b51bb66089490e565e3680dc6f5841..ad1e56fdcc7d10cd0a56337e6b17f0ab03f0625a 100644
--- a/media/filters/chunk_demuxer_unittest.cc
+++ b/media/filters/chunk_demuxer_unittest.cc
@@ -880,6 +880,23 @@ class ChunkDemuxerTest : public ::testing::TestWithParam<bool> {
       if (i > 0)
         ss << " ";
       ss << buffer->timestamp().InMilliseconds();
+
+      // Handle preroll buffers.
+      if (EndsWith(timestamps[i], "P", true)) {
+        scoped_refptr<DecoderBuffer> preroll_buffer;
+        preroll_buffer.swap(buffer);
+
+        // When a preroll buffer is encountered we should be able to request one
+        // more buffer.  The first buffer should have a timestamp equal to the
+        // second buffer and its discard_padding() should be its duration.
+        stream->Read(base::Bind(&ChunkDemuxerTest::StoreStatusAndBuffer,
+                                base::Unretained(this), &status, &buffer));
+        base::MessageLoop::current()->RunUntilIdle();
+        ASSERT_EQ(preroll_buffer->timestamp(), buffer->timestamp());
+        ASSERT_EQ(preroll_buffer->discard_padding().first,
+                  preroll_buffer->duration());
+        ss << "P";
+      }
     }
     EXPECT_EQ(expected, ss.str());
   }
@@ -3059,8 +3076,8 @@ TEST_P(ChunkDemuxerTest, AppendWindow_Video) {
   ASSERT_TRUE(InitDemuxer(HAS_VIDEO));
   DemuxerStream* stream = demuxer_->GetStream(DemuxerStream::VIDEO);
 
-  // Set the append window to [20,280).
-  append_window_start_for_next_append_ = base::TimeDelta::FromMilliseconds(20);
+  // Set the append window to [50,280).

[wolenetz, 2014/05/17 00:41:17]

Why increase 20 -> 50? Currently, video does not support partial append window
trimming, so preroll (or even partial append window trimming itself) shouldn't
change the result, below, right?
Perhaps video keyframe preroll and partial append window trimming should be
supported for video? (separate CL)

[DaleCurtis, 2014/05/17 00:55:41]

I changed them both because I thought it was a better test.

+  append_window_start_for_next_append_ = base::TimeDelta::FromMilliseconds(50);
   append_window_end_for_next_append_ = base::TimeDelta::FromMilliseconds(280);
 
   // Append a cluster that starts before and ends after the append window.
@@ -3087,8 +3104,8 @@ TEST_P(ChunkDemuxerTest, AppendWindow_Audio) {
   ASSERT_TRUE(InitDemuxer(HAS_AUDIO));
   DemuxerStream* stream = demuxer_->GetStream(DemuxerStream::AUDIO);
 
-  // Set the append window to [20,280).
-  append_window_start_for_next_append_ = base::TimeDelta::FromMilliseconds(20);
+  // Set the append window to [50,280).
+  append_window_start_for_next_append_ = base::TimeDelta::FromMilliseconds(50);
   append_window_end_for_next_append_ = base::TimeDelta::FromMilliseconds(280);
 
   // Append a cluster that starts before and ends after the append window.
@@ -3100,19 +3117,20 @@ TEST_P(ChunkDemuxerTest, AppendWindow_Audio) {
   // in the buffer. Also verify that buffers that start inside the
   // window and extend beyond the end of the window are not included.
   //
-  // The first 20ms of the first buffer should be trimmed off since it
-  // overlaps the start of the append window.
-  CheckExpectedRanges(kSourceId, "{ [20,270) }");
-  CheckExpectedBuffers(stream, "20 30 60 90 120 150 180 210 240");
+  // The first 20ms of the second buffer should be trimmed off since it
+  // overlaps the start of the append window.  The first buffer should be
+  // added as preroll to the second buffer.
+  CheckExpectedRanges(kSourceId, "{ [50,270) }");
+  CheckExpectedBuffers(stream, "50P 60 90 120 150 180 210 240");
 
-  // Extend the append window to [20,650).
+  // Extend the append window to [50,650).
   append_window_end_for_next_append_ = base::TimeDelta::FromMilliseconds(650);
 
   // Append more data and verify that a new range is created.
   AppendSingleStreamCluster(
       kSourceId, kAudioTrackNum,
       "360K 390K 420K 450K 480K 510K 540K 570K 600K 630K");
-  CheckExpectedRanges(kSourceId, "{ [20,270) [360,630) }");
+  CheckExpectedRanges(kSourceId, "{ [50,270) [360,630) }");
 }
 
 TEST_P(ChunkDemuxerTest, AppendWindow_AudioOverlapStartAndEnd) {