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

media/base/audio_buffer_converter.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/base/audio_buffer_converter.h"
 
 #include <cmath>
 
 #include "base/logging.h"
 #include "media/base/audio_buffer.h"
@@ skipping 209 matching lines @@
     }
 
     // Do the actual conversion.
     audio_converter_->Convert(output_bus.get());
     frames_remaining -= frames_this_iteration;
     buffered_input_frames_ -= frames_this_iteration * io_sample_rate_ratio_;
   }
 
   // Compute the timestamp.
   output_buffer->set_timestamp(timestamp_helper_.GetTimestamp());
+  output_buffer->set_duration(
+      timestamp_helper_.GetFrameDuration(request_frames));
   timestamp_helper_.AddFrames(request_frames);
 
   queued_outputs_.push_back(output_buffer);
 }
 
 void AudioBufferConverter::Flush() {
   if (!audio_converter_)
     return;
   is_flushing_ = true;
   ConvertIfPossible();
   is_flushing_ = false;
   audio_converter_->Reset();
   DCHECK_EQ(input_frames_, 0);
   DCHECK_EQ(last_input_buffer_offset_, 0);
   DCHECK_LT(buffered_input_frames_, 1.0);
   DCHECK(queued_inputs_.empty());
   buffered_input_frames_ = 0.0;
 }
 
 }  // namespace media