Support for AudioContextOptions latencyHint.

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

Index: third_party/WebKit/Source/modules/webaudio/AudioContext.cpp
diff --git a/third_party/WebKit/Source/modules/webaudio/AudioContext.cpp b/third_party/WebKit/Source/modules/webaudio/AudioContext.cpp
index 920678225ca55b9c22d8908fa4de6b3d7bce0f17..519458f7256948bf092bf4a30e7c9aecf6edb73d 100644
--- a/third_party/WebKit/Source/modules/webaudio/AudioContext.cpp
+++ b/third_party/WebKit/Source/modules/webaudio/AudioContext.cpp
@@ -11,8 +11,11 @@
 #include "core/dom/ExceptionCode.h"
 #include "core/frame/UseCounter.h"
 #include "modules/webaudio/AudioBufferCallback.h"
+#include "modules/webaudio/AudioContextOptions.h"
+#include "modules/webaudio/DefaultAudioDestinationNode.h"
 #include "platform/Histogram.h"
 #include "platform/audio/AudioUtilities.h"
+#include "public/platform/WebAudioLatencyHint.h"
 
 #if DEBUG_AUDIONODE_REFERENCES
 #include <stdio.h>
@@ -27,6 +30,7 @@ static unsigned s_hardwareContextCount = 0;
 static unsigned s_contextId = 0;
 
 AudioContext* AudioContext::create(Document& document,
+                                   const AudioContextOptions& contextOptions,
                                    ExceptionState& exceptionState) {
   DCHECK(isMainThread());
 
@@ -41,7 +45,14 @@ AudioContext* AudioContext::create(Document& document,
     return nullptr;
   }
 
-  AudioContext* audioContext = new AudioContext(document);
+  WebAudioLatencyHint latencyHint(WebAudioLatencyHint::CategoryInteractive);
+  if (contextOptions.latencyHint().isAudioContextLatencyCategory()) {
+    latencyHint = WebAudioLatencyHint(
+        contextOptions.latencyHint().getAsAudioContextLatencyCategory());
+  }
+  // TODO: add support for latencyHint().isDouble()
+
+  AudioContext* audioContext = new AudioContext(document, latencyHint);
   audioContext->suspendIfNeeded();
 
   if (!AudioUtilities::isValidAudioBufferSampleRate(
@@ -83,8 +94,12 @@ AudioContext* AudioContext::create(Document& document,
   return audioContext;
 }
 
-AudioContext::AudioContext(Document& document)
-    : BaseAudioContext(&document), m_contextId(s_contextId++) {}
+AudioContext::AudioContext(Document& document,
+                           const WebAudioLatencyHint& latencyHint)
+    : BaseAudioContext(&document), m_contextId(s_contextId++) {
+  m_destinationNode = DefaultAudioDestinationNode::create(this, latencyHint);
+  initialize();
+}
 
 AudioContext::~AudioContext() {
 #if DEBUG_AUDIONODE_REFERENCES
@@ -205,4 +220,8 @@ void AudioContext::stopRendering() {
   }
 }
 
+double AudioContext::baseLatency() const {
+  return framesPerBuffer() * 2 / static_cast<double>(sampleRate());
+}
+
 }  // namespace blink