Add constructors for WebAudio nodes

third_party/WebKit/Source/modules/webaudio/GainNode.h

Index: third_party/WebKit/Source/modules/webaudio/GainNode.h
diff --git a/third_party/WebKit/Source/modules/webaudio/GainNode.h b/third_party/WebKit/Source/modules/webaudio/GainNode.h
index 0f8cffbbd5ba297c65b83586f6ddadc5bef14d40..e6aa24c4746d7ca03d597c6decfcd6890c40902d 100644
--- a/third_party/WebKit/Source/modules/webaudio/GainNode.h
+++ b/third_party/WebKit/Source/modules/webaudio/GainNode.h
@@ -33,6 +33,7 @@
 namespace blink {
 
 class BaseAudioContext;
+class GainOptions;
 
 // GainNode is an AudioNode with one input and one output which applies a gain (volume) change to the audio signal.
 // De-zippering (smoothing) is applied when the gain value is changed dynamically.
@@ -60,6 +61,7 @@ class GainNode final : public AudioNode {
     DEFINE_WRAPPERTYPEINFO();
 public:
     static GainNode* create(BaseAudioContext&, ExceptionState&);
+    static GainNode* create(BaseAudioContext*, const GainOptions&, ExceptionState&);
     DECLARE_VIRTUAL_TRACE();
 
     AudioParam* gain() const;