Fix MSE GC, make it less aggressive, more spec-compliant

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 16ddff5b50529e8060164a486728d159bf5472e6..7b495061f349f254d92e08b625545c55d377a734 100644
--- a/media/filters/chunk_demuxer_unittest.cc
+++ b/media/filters/chunk_demuxer_unittest.cc
@@ -176,8 +176,11 @@ class ChunkDemuxerTest : public ::testing::Test {
         base::Bind(&ChunkDemuxerTest::DemuxerOpened, base::Unretained(this));
     Demuxer::EncryptedMediaInitDataCB encrypted_media_init_data_cb = base::Bind(
         &ChunkDemuxerTest::OnEncryptedMediaInitData, base::Unretained(this));
+    current_playback_position_ = kNoTimestamp();
     demuxer_.reset(new ChunkDemuxer(
         open_cb, encrypted_media_init_data_cb, base::Bind(&AddLogEntryForTest),
+        base::Bind(&ChunkDemuxerTest::GetCurrentPlaybackPosition,
+                   base::Unretained(this)),
         scoped_refptr<MediaLog>(new MediaLog()), true));
   }
 
@@ -1183,12 +1186,24 @@ class ChunkDemuxerTest : public ::testing::Test {
     return true;
   }
 
+  void SetCurrentPlaybackPosition(base::TimeDelta media_time) {
+    current_playback_position_ = media_time;
+  }
+
+  base::TimeDelta GetCurrentPlaybackPosition() {
+    return current_playback_position_;
+  }
+
   base::MessageLoop message_loop_;
   MockDemuxerHost host_;
 
   scoped_ptr<ChunkDemuxer> demuxer_;
   ChunkDemuxer::InitSegmentReceivedCB init_segment_received_cb_;
 
+  // Used to provide current playback position for ChunkDemuxer garbage
+  // collection algorithm.
+  base::TimeDelta current_playback_position_;
+
   base::TimeDelta append_window_start_for_next_append_;
   base::TimeDelta append_window_end_for_next_append_;
 
@@ -3334,7 +3349,7 @@ TEST_F(ChunkDemuxerTest, SetMemoryLimitType) {
 
   // Set different memory limits for audio and video.
   demuxer_->SetMemoryLimits(DemuxerStream::AUDIO, 10 * kBlockSize);
-  demuxer_->SetMemoryLimits(DemuxerStream::VIDEO, 5 * kBlockSize);
+  demuxer_->SetMemoryLimits(DemuxerStream::VIDEO, 5 * kBlockSize + 1);
 
   base::TimeDelta seek_time = base::TimeDelta::FromMilliseconds(1000);
 
@@ -3342,6 +3357,9 @@ TEST_F(ChunkDemuxerTest, SetMemoryLimitType) {
   AppendSingleStreamCluster(kSourceId, kAudioTrackNum, 0, 10);
   AppendSingleStreamCluster(kSourceId, kVideoTrackNum, 0, 5);
 
+  // We should be right at buffer limit, should pass
+  EXPECT_TRUE(demuxer_->EvictFrames());
+
   CheckExpectedRanges(DemuxerStream::AUDIO, "{ [0,230) }");
   CheckExpectedRanges(DemuxerStream::VIDEO, "{ [0,165) }");
 
@@ -3354,6 +3372,9 @@ TEST_F(ChunkDemuxerTest, SetMemoryLimitType) {
   AppendSingleStreamCluster(kSourceId, kVideoTrackNum,
                             seek_time.InMilliseconds(), 5);
 
+  // We should delete first append, and be exactly at buffer limit
+  EXPECT_TRUE(demuxer_->EvictFrames());
+
   // Verify that the old data, and nothing more, has been garbage collected.
   CheckExpectedRanges(DemuxerStream::AUDIO, "{ [1000,1230) }");
   CheckExpectedRanges(DemuxerStream::VIDEO, "{ [1000,1165) }");
@@ -3378,12 +3399,13 @@ TEST_F(ChunkDemuxerTest, GCDuringSeek) {
   // Signal that the second seek is starting.
   demuxer_->StartWaitingForSeek(seek_time2);
 
-  // Append data to satisfy the second seek. This append triggers
-  // the garbage collection logic since we set the memory limit to
-  // 5 blocks.
+  // Append data to satisfy the second seek.
   AppendSingleStreamCluster(kSourceId, kAudioTrackNum,
                             seek_time2.InMilliseconds(), 5);
 
+  // Should remove first append
+  EXPECT_TRUE(demuxer_->EvictFrames());
+
   // Verify that the buffers that cover |seek_time2| do not get
   // garbage collected.
   CheckExpectedRanges(kSourceId, "{ [500,615) }");
@@ -3391,15 +3413,46 @@ TEST_F(ChunkDemuxerTest, GCDuringSeek) {
   // Complete the seek.
   demuxer_->Seek(seek_time2, NewExpectedStatusCB(PIPELINE_OK));
 
-
   // Append more data and make sure that the blocks for |seek_time2|
   // don't get removed.
-  //
-  // NOTE: The current GC algorithm tries to preserve the GOP at the
-  //  current position as well as the last appended GOP. This is
-  //  why there are 2 ranges in the expectations.
   AppendSingleStreamCluster(kSourceId, kAudioTrackNum, 700, 5);
-  CheckExpectedRanges(kSourceId, "{ [500,592) [792,815) }");
+
+  // We should not delete things between head and last append, so buffer
+  // remains overfull.
+  EXPECT_FALSE(demuxer_->EvictFrames());
+
+  CheckExpectedRanges(kSourceId, "{ [500,615) [700,815) }");
+}
+
+TEST_F(ChunkDemuxerTest, GCKeepPlayhead) {
+  ASSERT_TRUE(InitDemuxer(HAS_AUDIO));
+
+  // Set different memory limits for audio and video.
+  demuxer_->SetMemoryLimits(DemuxerStream::AUDIO, 5 * kBlockSize);
+
+  // Set media time to report playback head at 0ms
+  SetCurrentPlaybackPosition(base::TimeDelta::FromMilliseconds(0));
+
+  // Append data at the start that can be garbage collected:
+  AppendSingleStreamCluster(kSourceId, kAudioTrackNum, 0, 10);
+
+  // We expect garbage collection to fail, as we don't want to spontaneously
+  // create gaps in source buffer stream. This could break playback for many
+  // clients, who don't bother to check ranges after append.
+  EXPECT_FALSE(demuxer_->EvictFrames());
+  CheckExpectedRanges(kSourceId, "{ [0,230) }");
+
+  // Seek, confirm that media time holds us at zero
+  base::TimeDelta seek_time = base::TimeDelta::FromMilliseconds(207);
+  Seek(seek_time);
+
+  EXPECT_FALSE(demuxer_->EvictFrames());
+  CheckExpectedRanges(kSourceId, "{ [0,230) }");
+
+  // Progress media time, show that we can collect up to that point
+  SetCurrentPlaybackPosition(base::TimeDelta::FromMilliseconds(69));
+  EXPECT_FALSE(demuxer_->EvictFrames());
+  CheckExpectedRanges(kSourceId, "{ [69,230) }");
 }
 
 TEST_F(ChunkDemuxerTest, AppendWindow_Video) {