Init alpha_codec_config_ in VpxEncoder

content/renderer/media_recorder/video_track_recorder.cc

 // Copyright 2015 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 "content/renderer/media_recorder/video_track_recorder.h"
 
 #include <utility>
 
 #include "base/bind.h"
 #include "base/logging.h"
@@ skipping 762 matching lines @@
   // Both |encoding_thread| and |encoder| will be destroyed at end-of-scope.
 }
 
 VpxEncoder::VpxEncoder(
     bool use_vp9,
     const VideoTrackRecorder::OnEncodedVideoCB& on_encoded_video_callback,
     int32_t bits_per_second)
     : Encoder(on_encoded_video_callback, bits_per_second),
       use_vp9_(use_vp9) {
   codec_config_.g_timebase.den = 0;  // Not initialized.
+  alpha_codec_config_.g_timebase.den = 0;  // Not initialized.
   DCHECK(encoding_thread_->IsRunning());
 }
 
 VpxEncoder::~VpxEncoder() {
   main_task_runner_->PostTask(FROM_HERE,
                               base::Bind(&VpxEncoder::ShutdownEncoder,
                                          base::Passed(&encoding_thread_),
                                          base::Passed(&encoder_)));
 }
 
@@ skipping 437 matching lines @@
     encoder_->SetPaused(paused_before_init_);
 
   // StartFrameEncode() will be called on Render IO thread.
   MediaStreamVideoSink::ConnectToTrack(
       track_,
       base::Bind(&VideoTrackRecorder::Encoder::StartFrameEncode, encoder_),
       false);
 }
 
 }  // namespace content