Introduce the playback time into the MSE garbage collection.

media/filters/source_buffer_stream.h

Index: media/filters/source_buffer_stream.h
diff --git a/media/filters/source_buffer_stream.h b/media/filters/source_buffer_stream.h
index 95b2e0970b16ecbde8e60307e9bdc5d3e07625f8..877f667927c9af9646de53224eea09f5ac7117c9 100644
--- a/media/filters/source_buffer_stream.h
+++ b/media/filters/source_buffer_stream.h
@@ -74,7 +74,8 @@ class MEDIA_EXPORT SourceBufferStream {
   // presentation order and are non-overlapping.
   // Returns true if Append() was successful, false if |buffers| are not added.
   // TODO(vrk): Implement garbage collection. (crbug.com/125070)
-  bool Append(const BufferQueue& buffers);
+  bool Append(const BufferQueue& buffers,
+              base::TimeDelta media_time);
 
   // Removes buffers between |start| and |end| according to the steps
   // in the "Coded Frame Removal Algorithm" in the Media Source
@@ -86,6 +87,12 @@ class MEDIA_EXPORT SourceBufferStream {
   void Remove(base::TimeDelta start, base::TimeDelta end,
               base::TimeDelta duration);
 
+  // Update the playback time.
+  // This playback time is used to avoid garbage collecting buffers
+  // corresponding to the playback time:
+  // MSE spec - 2.4.4 SourceBuffer Monitoring.
+  void NotifyMediaTimeUpdate(base::TimeDelta media_time);
+
   // Changes the SourceBufferStream's state so that it will start returning
   // buffers starting from the closest keyframe before |timestamp|.
   void Seek(base::TimeDelta timestamp);
@@ -149,13 +156,15 @@ class MEDIA_EXPORT SourceBufferStream {
   typedef std::list<SourceBufferRange*> RangeList;
 
   // Frees up space if the SourceBufferStream is taking up too much memory.
-  void GarbageCollectIfNeeded();
+  void GarbageCollectIfNeeded(base::TimeDelta media_time);
 
   // Attempts to delete approximately |total_bytes_to_free| amount of data
   // |ranges_|, starting at the front of |ranges_| and moving linearly forward
   // through the buffers. Deletes starting from the back if |reverse_direction|
   // is true. Returns the number of bytes freed.
-  int FreeBuffers(int total_bytes_to_free, bool reverse_direction);
+  int FreeBuffers(int total_bytes_to_free,
+                  bool reverse_direction,
+                  base::TimeDelta media_time);
 
   // Attempts to delete approximately |total_bytes_to_free| amount of data from
   // |ranges_|, starting after the last appended buffer before the current
@@ -368,6 +377,11 @@ class MEDIA_EXPORT SourceBufferStream {
   // emptied.
   SourceBufferRange* selected_range_;
 
+  // Current media time.
+  // This does not need to be very accurate as long as it represents a lower
+  // bound of the media time.
+  base::TimeDelta current_media_time_;
+
   // Queue of the next buffers to be returned from calls to GetNextBuffer(). If
   // |track_buffer_| is empty, return buffers from |selected_range_|.
   BufferQueue track_buffer_;