media: Prefer decrypting pipeline when CDM is attached

media/filters/decoder_stream.cc

 // Copyright 2014 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/decoder_stream.h"
 
 #include <utility>
 
 #include "base/bind.h"
 #include "base/callback_helpers.h"
@@ skipping 233 matching lines @@
 
 template <DemuxerStream::Type StreamType>
 base::TimeDelta DecoderStream<StreamType>::AverageDuration() const {
   DCHECK(task_runner_->BelongsToCurrentThread());
   return duration_tracker_.count() ? duration_tracker_.Average()
                                    : base::TimeDelta();
 }
 
 template <DemuxerStream::Type StreamType>
 void DecoderStream<StreamType>::SelectDecoder() {
+  // If we are already using DecryptingDemuxerStream (DDS), e.g. during
+  // fallback, the |stream_| will always be clear. In this case, no need pass in
+  // the |cdm_context_|. This will also help prevent creating a new DDS on top
+  // of the current DDS.
+  CdmContext* cdm_context = decrypting_demuxer_stream_ ? nullptr : cdm_context_;
+
   decoder_selector_->SelectDecoder(
-      &traits_, stream_, cdm_context_,
+      &traits_, stream_, cdm_context,
       base::Bind(&DecoderStream<StreamType>::OnDecoderSelected,
                  weak_factory_.GetWeakPtr()),
       base::Bind(&DecoderStream<StreamType>::OnDecodeOutputReady,
                  fallback_weak_factory_.GetWeakPtr()),
       waiting_for_decryption_key_cb_);
 }
 
 template <DemuxerStream::Type StreamType>
 void DecoderStream<StreamType>::OnDecoderSelected(
     std::unique_ptr<Decoder> selected_decoder,
@@ skipping 508 matching lines @@
   }
 
   // The resetting process will be continued in OnDecoderReinitialized().
   ReinitializeDecoder();
 }
 
 template class DecoderStream<DemuxerStream::VIDEO>;
 template class DecoderStream<DemuxerStream::AUDIO>;
 
 }  // namespace media