Revert of Remove AudioBuffer::set_duration(), instead base on frames.

media/filters/decrypting_audio_decoder.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/decrypting_audio_decoder.h"
 
 #include <cstdlib>
 
 #include "base/bind.h"
 #include "base/callback_helpers.h"
@@ skipping 353 matching lines @@
 
     base::TimeDelta current_time = timestamp_helper_->GetTimestamp();
     if (IsOutOfSync(current_time, frame->timestamp())) {
       DVLOG(1) << "Timestamp returned by the decoder ("
                << frame->timestamp().InMilliseconds() << " ms)"
                << " does not match the input timestamp and number of samples"
                << " decoded (" << current_time.InMilliseconds() << " ms).";
     }
 
     frame->set_timestamp(current_time);
+    frame->set_duration(
+        timestamp_helper_->GetFrameDuration(frame->frame_count()));
     timestamp_helper_->AddFrames(frame->frame_count());
   }
 }
 
 }  // namespace media