Support AudioContextOptions latencyHint as double.

content/renderer/media/renderer_webaudiodevice_impl.cc

Index: content/renderer/media/renderer_webaudiodevice_impl.cc
diff --git a/content/renderer/media/renderer_webaudiodevice_impl.cc b/content/renderer/media/renderer_webaudiodevice_impl.cc
index 2c4f81b185d74fe96ab0a25d677a67fd0d3d9296..8d1f0d82c3618a21dd70cd30b5e880f6d380bbc8 100644
--- a/content/renderer/media/renderer_webaudiodevice_impl.cc
+++ b/content/renderer/media/renderer_webaudiodevice_impl.cc
@@ -41,8 +41,7 @@ AudioDeviceFactory::SourceType GetLatencyHintSourceType(
     case WebAudioLatencyHint::kCategoryPlayback:
       return AudioDeviceFactory::kSourceWebAudioPlayback;
     case WebAudioLatencyHint::kCategoryExact:
-      // TODO implement CategoryExact
-      return AudioDeviceFactory::kSourceWebAudioInteractive;
+      return AudioDeviceFactory::kSourceWebAudioExact;
   }
   NOTREACHED();
   return AudioDeviceFactory::kSourceWebAudioInteractive;
@@ -128,7 +127,14 @@ RendererWebAudioDeviceImpl::RendererWebAudioDeviceImpl(
           hardware_params.sample_rate(), 0);
       break;
     case media::AudioLatency::LATENCY_EXACT_MS:
-    // TODO(olka): add support when WebAudio requires it.
+      output_buffer_size =
+          latency_hint.seconds() * hardware_params.sample_rate(),
+      output_buffer_size =
+          std::max(std::min(output_buffer_size,
+                            media::AudioLatency::GetHighLatencyBufferSize(
+                                hardware_params.sample_rate(), 0)),
+                   hardware_params.frames_per_buffer());

[o1ka, 2017/03/14 15:55:43]

Looks like we need something like media::AudioLatency::GetExactBufferSize()?

[Andrew MacPherson, 2017/03/15 15:08:17]

Done, I've added this now taking a parameter for the preferred size, min, and
max, let me know if that makes sense!

+      break;
     default:
       NOTREACHED();
   }