MSE: Protect better against out-of-sequence parser callbacks

media/filters/media_source_state.h

 // Copyright (c) 2016 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.
 
 #ifndef MEDIA_FILTERS_MEDIA_SOURCE_STATE_H_
 #define MEDIA_FILTERS_MEDIA_SOURCE_STATE_H_
 
 #include <list>
 
 #include "base/bind.h"
@@ skipping 98 matching lines @@
   bool IsSeekWaitingForData() const;
 
   typedef std::list<Ranges<TimeDelta>> RangesList;
   static Ranges<TimeDelta> ComputeRangesIntersection(
       const RangesList& activeRanges,
       bool ended);
 
   void SetTracksWatcher(const Demuxer::MediaTracksUpdatedCB& tracks_updated_cb);
 
  private:
+  // State advances through this list. The intent is to ensure at least one
+  // config is received prior to parser calling initialization callback, and
+  // that such initialization callback occurs at most once per parser.
+  enum State {
+    UNINITIALIZED = 0,
+    PENDING_PARSER_CONFIG,
+    PENDING_PARSER_INIT,
+    PARSER_INITIALIZED
+  };
+
   // Called by the |stream_parser_| when a new initialization segment is
   // encountered.
   // Returns true on a successful call. Returns false if an error occurred while
   // processing decoder configurations.
   bool OnNewConfigs(bool allow_audio,
                     bool allow_video,
                     scoped_ptr<MediaTracks> tracks,
                     const StreamParser::TextTrackConfigMap& text_configs);
 
   // Called by the |stream_parser_| at the beginning of a new media segment.
@@ skipping 56 matching lines @@
   ChunkDemuxerStream* audio_;  // Not owned by |this|.
   ChunkDemuxerStream* video_;  // Not owned by |this|.
 
   typedef std::map<StreamParser::TrackId, ChunkDemuxerStream*> TextStreamMap;
   TextStreamMap text_stream_map_;  // |this| owns the map's stream pointers.
 
   scoped_ptr<FrameProcessor> frame_processor_;
   scoped_refptr<MediaLog> media_log_;
   StreamParser::InitCB init_cb_;
 
+  State state_;
+
   // During Append(), OnNewConfigs() will trigger the initialization segment
   // received algorithm. Note, the MSE spec explicitly disallows this algorithm
   // during an Abort(), since Abort() is allowed only to emit coded frames, and
   // only if the parser is PARSING_MEDIA_SEGMENT (not an INIT segment). So we
   // also have a flag here that indicates if Append is in progress and we can
   // invoke this callback.
   Demuxer::MediaTracksUpdatedCB init_segment_received_cb_;
   bool append_in_progress_ = false;
 
   // Indicates that timestampOffset should be updated automatically during
   // OnNewBuffers() based on the earliest end timestamp of the buffers provided.
   // TODO(wolenetz): Refactor this function while integrating April 29, 2014
   // changes to MSE spec. See http://crbug.com/371499.
   bool auto_update_timestamp_offset_;
 
   DISALLOW_COPY_AND_ASSIGN(MediaSourceState);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_FILTERS_MEDIA_SOURCE_STATE_H_