Fix WebAudio support for discrete channel layouts.

content/renderer/media/renderer_webaudiodevice_impl.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 "content/renderer/media/renderer_webaudiodevice_impl.h"
 
 #include <stddef.h>
 
 #include <string>
 
@@ skipping 58 matching lines @@
     const url::Origin& security_origin) {
   return AudioDeviceFactory::GetOutputDeviceInfo(frame_id, session_id,
                                                  device_id, security_origin)
       .output_params();
 }
 
 }  // namespace
 
 RendererWebAudioDeviceImpl* RendererWebAudioDeviceImpl::Create(
     media::ChannelLayout layout,
+    int channels,
     const blink::WebAudioLatencyHint& latency_hint,
     WebAudioDevice::RenderCallback* callback,
     int session_id,
     const url::Origin& security_origin) {
-  return new RendererWebAudioDeviceImpl(layout, latency_hint, callback,
-                                        session_id, security_origin,
+  return new RendererWebAudioDeviceImpl(layout, channels, latency_hint,
+                                        callback, session_id, security_origin,
                                         base::Bind(&GetOutputDeviceParameters),
                                         base::Bind(&FrameIdFromCurrentContext));
 }
 
 RendererWebAudioDeviceImpl::RendererWebAudioDeviceImpl(
     media::ChannelLayout layout,
+    int channels,
     const blink::WebAudioLatencyHint& latency_hint,
     WebAudioDevice::RenderCallback* callback,
     int session_id,
     const url::Origin& security_origin,
     const OutputDeviceParamsCallback& device_params_cb,
     const RenderFrameIdCallback& render_frame_id_cb)
     : latency_hint_(latency_hint),
       client_callback_(callback),
       session_id_(session_id),
       security_origin_(security_origin),
@@ skipping 27 matching lines @@
     case media::AudioLatency::LATENCY_EXACT_MS:
     // TODO(olka): add support when WebAudio requires it.
     default:
       NOTREACHED();
   }
 
   DCHECK_NE(output_buffer_size, 0);
 
   sink_params_.Reset(media::AudioParameters::AUDIO_PCM_LOW_LATENCY, layout,
                      hardware_params.sample_rate(), 16, output_buffer_size);
+  sink_params_.set_channels_for_discrete(channels);

[hongchan, 2017/02/23 18:43:37]

Can we add a comment why this is necessary here? Without this, the discrete
layout will crash. Right?

[DaleCurtis, 2017/02/23 20:06:07]

Done.

 
   // Specify the latency info to be passed to the browser side.
   sink_params_.set_latency_tag(latency);
 }
 
 RendererWebAudioDeviceImpl::~RendererWebAudioDeviceImpl() {
   DCHECK(!sink_);
 }
 
 void RendererWebAudioDeviceImpl::start() {
@@ skipping 77 matching lines @@
 const scoped_refptr<base::SingleThreadTaskRunner>&
 RendererWebAudioDeviceImpl::GetMediaTaskRunner() {
   if (!media_task_runner_) {
     media_task_runner_ =
         RenderThreadImpl::current()->GetMediaThreadTaskRunner();
   }
   return media_task_runner_;
 }
 
 }  // namespace content