Make OS audio buffer size limits visible.

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>
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/logging.h"
 #include "base/time/time.h"
 #include "build/build_config.h"
 #include "content/renderer/media/audio_device_factory.h"
 #include "content/renderer/render_frame_impl.h"
 #include "content/renderer/render_thread_impl.h"
+#include "media/audio/audio_manager.h"
 #include "media/base/audio_timestamp_helper.h"
 #include "media/base/silent_sink_suspender.h"
 #include "third_party/WebKit/public/web/WebLocalFrame.h"
 #include "third_party/WebKit/public/web/WebView.h"
 
 using blink::WebAudioDevice;
 using blink::WebAudioLatencyHint;
 using blink::WebLocalFrame;
 using blink::WebVector;
 using blink::WebView;
@@ skipping 29 matching lines @@
       break;
     case media::AudioLatency::LATENCY_RTC:
       return media::AudioLatency::GetRtcBufferSize(
           hardware_params.sample_rate(), hardware_params.frames_per_buffer());
       break;
     case media::AudioLatency::LATENCY_PLAYBACK:
       return media::AudioLatency::GetHighLatencyBufferSize(
           hardware_params.sample_rate(), 0);
       break;
     case media::AudioLatency::LATENCY_EXACT_MS:
-      // TODO(andrew.macpherson@soundtrap.com): http://crbug.com/708917
-      return std::min(4096,
+      return std::min(media::AudioManager::GetMaximumAudioBufferSize(

[o1ka, 2017/05/29 16:11:33]

AudioManager is browser side only entity and cannot be used in the renderer.
Why cannot the code live in AudioLatency?

+                          hardware_params.sample_rate()),
                       media::AudioLatency::GetExactBufferSize(
                           base::TimeDelta::FromSecondsD(latency_hint.Seconds()),
                           hardware_params.sample_rate(),
-                          hardware_params.frames_per_buffer()));
+                          media::AudioManager::GetMinimumAudioBufferSize(
+                              hardware_params.sample_rate())));
       break;
     default:
       NOTREACHED();
   }
   return 0;
 }
 
 int FrameIdFromCurrentContext() {
   // Assumption: This method is being invoked within a V8 call stack.  CHECKs
   // will fail in the call to frameForCurrentContext() otherwise.
@@ skipping 157 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