Introduce the playback time into the MSE garbage collection.

media/filters/source_buffer_stream.cc

Index: media/filters/source_buffer_stream.cc
diff --git a/media/filters/source_buffer_stream.cc b/media/filters/source_buffer_stream.cc
index fe22b4a795eaf0f0ed102cdc93c748ce005ffc8e..8381ab07be5df8ab61e14de5909e6b4c104a0c1c 100644
--- a/media/filters/source_buffer_stream.cc
+++ b/media/filters/source_buffer_stream.cc
@@ -126,6 +126,10 @@ class SourceBufferRange {
       base::TimeDelta start_timestamp, base::TimeDelta end_timestamp,
       int bytes_to_free, base::TimeDelta* end_removal_timestamp);
 
+  // Indicates whether the GOP at the beginning of the range
+  // has timestamps all lower than |media_time|.
+  bool FirstGOPEarlierThanMediaTime(base::TimeDelta media_time) const;
+
   // Indicates whether the GOP at the beginning or end of the range contains the
   // next buffer position.
   bool FirstGOPContainsNextBufferPosition() const;
@@ -351,6 +355,7 @@ SourceBufferStream::SourceBufferStream(const AudioDecoderConfig& audio_config,
       end_of_stream_(false),
       seek_buffer_timestamp_(kNoTimestamp()),
       selected_range_(NULL),
+      current_media_time_(kNoTimestamp()),
       media_segment_start_time_(kNoTimestamp()),
       range_for_next_append_(ranges_.end()),
       new_media_segment_(false),
@@ -377,6 +382,7 @@ SourceBufferStream::SourceBufferStream(const VideoDecoderConfig& video_config,
       end_of_stream_(false),
       seek_buffer_timestamp_(kNoTimestamp()),
       selected_range_(NULL),
+      current_media_time_(kNoTimestamp()),
       media_segment_start_time_(kNoTimestamp()),
       range_for_next_append_(ranges_.end()),
       new_media_segment_(false),
@@ -404,6 +410,7 @@ SourceBufferStream::SourceBufferStream(const TextTrackConfig& text_config,
       end_of_stream_(false),
       seek_buffer_timestamp_(kNoTimestamp()),
       selected_range_(NULL),
+      current_media_time_(kNoTimestamp()),
       media_segment_start_time_(kNoTimestamp()),
       range_for_next_append_(ranges_.end()),
       new_media_segment_(false),
@@ -902,6 +909,10 @@ int SourceBufferStream::FreeBuffers(int total_bytes_to_free,
         DCHECK_EQ(current_range, selected_range_);
         break;
       }
+      if (current_media_time_ != kNoTimestamp() &&
+          !current_range->FirstGOPEarlierThanMediaTime(current_media_time_)) {

[acolwell GONE FROM CHROMIUM, 2014/06/19 16:00:25]

Don't you really want FirstGOPContainsMediaTime(current_media_time) ? 

+        break;
+      }
       bytes_deleted = current_range->DeleteGOPFromFront(&buffers);
     }
 
@@ -1074,10 +1085,23 @@ void SourceBufferStream::MergeWithAdjacentRangeIfNecessary(
   DeleteAndRemoveRange(&next_range_itr);
 }
 
+void SourceBufferStream::NotifyMediaTimeUpdate(base::TimeDelta media_time) {
+  if (current_media_time_ != kNoTimestamp() &&
+      media_time < current_media_time_) {
+    LOG(WARNING) << "Time should be monotonically increasing: "
+                 << media_time.InMilliseconds()
+                 << " " << current_media_time_.InMilliseconds();
+    return;
+  }
+  current_media_time_ = media_time;
+}
+
 void SourceBufferStream::Seek(base::TimeDelta timestamp) {
   DCHECK(timestamp >= base::TimeDelta());
   ResetSeekState();
 
+  current_media_time_ = kNoTimestamp();
+
   if (ShouldSeekToStartOfBuffered(timestamp)) {
     ranges_.front()->SeekToStart();
     SetSelectedRange(ranges_.front());
@@ -1988,6 +2012,16 @@ int SourceBufferRange::GetRemovalGOP(
   return bytes_removed;
 }
 
+bool SourceBufferRange::FirstGOPEarlierThanMediaTime(
+    base::TimeDelta media_time) const {
+  if (keyframe_map_.size() == 1u)
+    return (GetEndTimestamp() < media_time);
+
+  KeyframeMap::const_iterator second_gop = keyframe_map_.begin();
+  ++second_gop;
+  return second_gop->first <= media_time;
+}
+
 bool SourceBufferRange::FirstGOPContainsNextBufferPosition() const {
   if (!HasNextBufferPosition())
     return false;