Support for AudioContextOptions latencyHint.

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

Index: third_party/WebKit/Source/modules/webaudio/BaseAudioContext.cpp
diff --git a/third_party/WebKit/Source/modules/webaudio/BaseAudioContext.cpp b/third_party/WebKit/Source/modules/webaudio/BaseAudioContext.cpp
index 020e539047db244fcc9878bc8f9e5da1fe0beefa..ef5124438574cc2776fe893481e9cc0bd8f1c517 100644
--- a/third_party/WebKit/Source/modules/webaudio/BaseAudioContext.cpp
+++ b/third_party/WebKit/Source/modules/webaudio/BaseAudioContext.cpp
@@ -44,6 +44,7 @@
 #include "modules/webaudio/AudioBufferCallback.h"
 #include "modules/webaudio/AudioBufferSourceNode.h"
 #include "modules/webaudio/AudioContext.h"
+#include "modules/webaudio/AudioContextOptions.h"
 #include "modules/webaudio/AudioListener.h"
 #include "modules/webaudio/AudioNodeInput.h"
 #include "modules/webaudio/AudioNodeOutput.h"
@@ -75,20 +76,24 @@
 #include "platform/UserGestureIndicator.h"
 #include "platform/audio/IIRFilter.h"
 #include "public/platform/Platform.h"
+#include "public/platform/WebAudioLatencyHint.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 WebAudioLatencyHint& latencyHint,

[Raymond Toy, 2016/11/15 18:16:17]

Since OfflineAudioContext does not have a latency hint, it seems unexpected to
have BaseAudioContext support a latency hint. I was expecting this to be defined
only for an AudioContext.

(However, the current separation between offline and realtime contexts is not
very good, so maybe this is the best way for now.)

[Andrew MacPherson, 2016/11/16 10:58:29]

I think we need the latencyHint value to be passed into the
DefaultAudioDestinationNode so I wasn't sure if the right thing was to pass it
in here or else to move the DefaultAudioDestinationNode up to be owned by the
AudioContext (or something else). There seem to be two constructors for the
BaseAudioContext, one that's used by the AudioContext and one that's used by the
OfflineAudioContext and this should only affect the one used by the AudioContext
(and we don't store the latencyHint as a member on the BaseAudioContext). Let me
know what you think.

+    ExceptionState& exceptionState) {
+  return AudioContext::create(document, latencyHint, exceptionState);
 }
 
 // FIXME(dominicc): Devolve these constructors to AudioContext
 // and OfflineAudioContext respectively.
 
 // Constructor for rendering to the audio hardware.
-BaseAudioContext::BaseAudioContext(Document* document)
+BaseAudioContext::BaseAudioContext(Document* document,
+                                   const WebAudioLatencyHint& latencyHint)
     : ActiveScriptWrappable(this),
       ActiveDOMObject(document),
       m_destinationNode(nullptr),
@@ -112,7 +117,7 @@ BaseAudioContext::BaseAudioContext(Document* document)
     m_userGestureRequired = true;
   }
 
-  m_destinationNode = DefaultAudioDestinationNode::create(this);
+  m_destinationNode = DefaultAudioDestinationNode::create(this, latencyHint);
 
   initialize();
 }