Use ffmpeg for opus decoding, no need to maintain our decoder.

media/base/audio_discard_helper.h

 // 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.
 
 #ifndef MEDIA_BASE_AUDIO_DISCARD_HELPER_H_
 #define MEDIA_BASE_AUDIO_DISCARD_HELPER_H_
 
 #include <stddef.h>
 
 #include "base/macros.h"
@@ skipping 16 matching lines @@
   //
   // |decoder_delay| is the number of frames a decoder will output before data
   // corresponding to the first encoded buffer is output.  Callers only need to
   // specify this if the decoder inserts frames which have no corresponding
   // encoded buffer.
   //
   // For example, most MP3 decoders will output 529 junk frames before the data
   // corresponding to the first encoded buffer is output.  These frames are not
   // represented in the encoded data stream and instead are an artifact of how
   // most MP3 decoders work.  See http://lame.sourceforge.net/tech-FAQ.txt
-  AudioDiscardHelper(int sample_rate, size_t decoder_delay);
+  AudioDiscardHelper(int sample_rate,
+                     size_t decoder_delay,
+                     bool delayed_discard);
   ~AudioDiscardHelper();
 
   // Converts a TimeDelta to a frame count based on the constructed sample rate.
   // |duration| must be positive.
   size_t TimeDeltaToFrames(base::TimeDelta duration) const;
 
   // Resets internal state and indicates that |initial_discard| of upcoming
   // frames should be discarded.
   void Reset(size_t initial_discard);
 
@@ skipping 35 matching lines @@
   // associated buffer.
   size_t discard_frames_;
 
   // The last encoded buffer timestamp seen by ProcessBuffers() or kNoTimestamp
   // if no buffers have been seen thus far.  Used to issue warnings for buffer
   // sequences with non-monotonic timestamps.
   base::TimeDelta last_input_timestamp_;
 
   // Certain codecs require two encoded buffers before they'll output the first
   // decoded buffer.  In this case DiscardPadding must be carried over from the
   // previous encoded buffer.  Enabled automatically if an encoded buffer is

[wolenetz, 2016/10/21 22:30:58]

It's const, ctor initialized now, so no longer enable-able automatically by an
instance method like ProcessBuffers().

[wolenetz, 2016/11/18 00:36:41]

In patch set 2, this code comment still incorrectly mentions "Enabled
automatically if...ProcessBuffers()". Instead, it's set by the ctor.

[DaleCurtis, 2016/11/18 00:51:27]

Fixed.

   // given to ProcessBuffers() with a NULL decoded buffer.
-  bool delayed_discard_;
+  const bool delayed_discard_;
   DecoderBuffer::DiscardPadding delayed_discard_padding_;
 
   // When |decoder_delay_| > 0, the number of frames which should be discarded
   // from the next buffer.  The index at which to start discarding is calculated
   // by subtracting |delayed_end_discard_| from |decoder_delay_|.
   size_t delayed_end_discard_;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(AudioDiscardHelper);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_BASE_AUDIO_DISCARD_HELPER_H_