Remove FFmpegDemuxer DCHECKs that are handled via conditionals.

media/filters/ffmpeg_demuxer.cc

 // Copyright (c) 2012 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.
 
 #include "media/filters/ffmpeg_demuxer.h"
 
 #include <algorithm>
 #include <memory>
 #include <set>
 #include <utility>
@@ skipping 1735 matching lines @@
       duration_known_ = true;
       duration_ = max_duration;
     }
 
     // If we have reached the end of stream, tell the downstream filters about
     // the event.
     StreamHasEnded();
     return;
   }
 
-  // Queue the packet with the appropriate stream.
-  DCHECK_GE(packet->stream_index, 0);
-  DCHECK_LT(packet->stream_index, static_cast<int>(streams_.size()));
-
-  // Defend against ffmpeg giving us a bad stream index.
+  // Queue the packet with the appropriate stream; we must defend against ffmpeg
+  // giving us a bad stream index.  See http://crbug.com/698549 for example.
   if (packet->stream_index >= 0 &&
       packet->stream_index < static_cast<int>(streams_.size()) &&
       streams_[packet->stream_index]) {
     // TODO(scherkus): Fix demuxing upstream to never return packets w/o data
     // when av_read_frame() returns success code. See bug comment for ideas:
     //
     // https://code.google.com/p/chromium/issues/detail?id=169133#c10
     if (!packet->data) {
       ScopedAVPacket new_packet(new AVPacket());
       av_new_packet(new_packet.get(), 0);
@@ skipping 68 matching lines @@
 
 void FFmpegDemuxer::SetLiveness(DemuxerStream::Liveness liveness) {
   DCHECK(task_runner_->BelongsToCurrentThread());
   for (const auto& stream : streams_) {
     if (stream)
       stream->SetLiveness(liveness);
   }
 }
 
 }  // namespace media