Support for AudioContextOptions latencyHint.

third_party/WebKit/Source/modules/webaudio/BaseAudioContext.cpp

 /*
  * Copyright (C) 2010, Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1.  Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 34 matching lines @@
 #include "modules/webaudio/AudioBufferSourceNode.h"
 #include "modules/webaudio/AudioContext.h"
 #include "modules/webaudio/AudioListener.h"
 #include "modules/webaudio/AudioNodeInput.h"
 #include "modules/webaudio/AudioNodeOutput.h"
 #include "modules/webaudio/BiquadFilterNode.h"
 #include "modules/webaudio/ChannelMergerNode.h"
 #include "modules/webaudio/ChannelSplitterNode.h"
 #include "modules/webaudio/ConstantSourceNode.h"
 #include "modules/webaudio/ConvolverNode.h"
-#include "modules/webaudio/DefaultAudioDestinationNode.h"
 #include "modules/webaudio/DelayNode.h"
 #include "modules/webaudio/DynamicsCompressorNode.h"
 #include "modules/webaudio/GainNode.h"
 #include "modules/webaudio/IIRFilterNode.h"
 #include "modules/webaudio/MediaElementAudioSourceNode.h"
 #include "modules/webaudio/MediaStreamAudioDestinationNode.h"
 #include "modules/webaudio/MediaStreamAudioSourceNode.h"
 #include "modules/webaudio/OfflineAudioCompletionEvent.h"
 #include "modules/webaudio/OfflineAudioContext.h"
 #include "modules/webaudio/OfflineAudioDestinationNode.h"
 #include "modules/webaudio/OscillatorNode.h"
 #include "modules/webaudio/PannerNode.h"
 #include "modules/webaudio/PeriodicWave.h"
 #include "modules/webaudio/PeriodicWaveConstraints.h"
 #include "modules/webaudio/ScriptProcessorNode.h"
 #include "modules/webaudio/StereoPannerNode.h"
 #include "modules/webaudio/WaveShaperNode.h"
 #include "platform/CrossThreadFunctional.h"
 #include "platform/Histogram.h"
 #include "platform/UserGestureIndicator.h"
 #include "platform/audio/IIRFilter.h"
 #include "public/platform/Platform.h"
 #include "wtf/text/WTFString.h"
 
 namespace blink {
 
-BaseAudioContext* BaseAudioContext::create(Document& document,
-                                           ExceptionState& exceptionState) {
-  return AudioContext::create(document, exceptionState);
+BaseAudioContext* BaseAudioContext::create(
+    Document& document,
+    const AudioContextOptions& contextOptions,
+    ExceptionState& exceptionState) {
+  return AudioContext::create(document, contextOptions, exceptionState);
 }
 
 // FIXME(dominicc): Devolve these constructors to AudioContext
 // and OfflineAudioContext respectively.
 
 // Constructor for rendering to the audio hardware.
 BaseAudioContext::BaseAudioContext(Document* document)
     : ActiveScriptWrappable(this),
       ActiveDOMObject(document),
       m_destinationNode(nullptr),
       m_isCleared(false),
       m_isResolvingResumePromises(false),
       m_userGestureRequired(false),
       m_connectionCount(0),
       m_deferredTaskHandler(DeferredTaskHandler::create()),
       m_contextState(Suspended),
       m_closedContextSampleRate(-1),
       m_periodicWaveSine(nullptr),
       m_periodicWaveSquare(nullptr),
       m_periodicWaveSawtooth(nullptr),
       m_periodicWaveTriangle(nullptr) {
   // If mediaPlaybackRequiresUserGesture is enabled, cross origin iframes will
   // require user gesture for the AudioContext to produce sound.
   if (document->settings() &&
       document->settings()->mediaPlaybackRequiresUserGesture() &&
       document->frame() && document->frame()->isCrossOriginSubframe()) {
     m_autoplayStatus = AutoplayStatus::AutoplayStatusFailed;
     m_userGestureRequired = true;
   }
-
-  m_destinationNode = DefaultAudioDestinationNode::create(this);
-
-  initialize();

[Raymond Toy, 2016/12/08 17:14:38]

Ah, nice catch.  You removed this because OfflineAudioContext was calling this
to create the context, which sets m_destinationNode here, but the
OfflineAudioContext would replace it with another right away.

Right?

[Andrew MacPherson, 2016/12/09 12:34:14]

The OfflineAudioContext actually uses a different constructor so it wasn't being
set here in that case, however now that the DefaultAudioDestinationNode takes a
WebAudioLatencyHint parameter I figured it would make sense to move these lines
into the AudioContext so that the BaseAudioContext doesn't need to know about
the WebAudioLatencyHint. This also made it so that both the OfflineAudioContext
and the AudioContext are now responsible for the m_destinationNode rather than
the BaseAudioContext creating it in one case only but not the other.

[Raymond Toy, 2016/12/13 15:53:11]

Thanks for the explanation.  This makes the code much nicer.

 }
 
 // Constructor for offline (non-realtime) rendering.
 BaseAudioContext::BaseAudioContext(Document* document,
                                    unsigned numberOfChannels,
                                    size_t numberOfFrames,
                                    float sampleRate)
     : ActiveScriptWrappable(this),
       ActiveDOMObject(document),
       m_destinationNode(nullptr),
@@ skipping 753 matching lines @@
 }
 
 SecurityOrigin* BaseAudioContext::getSecurityOrigin() const {
   if (getExecutionContext())
     return getExecutionContext()->getSecurityOrigin();
 
   return nullptr;
 }
 
 }  // namespace blink