Implement IIRFilter node for WebAudio.

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

Index: third_party/WebKit/Source/modules/webaudio/AbstractAudioContext.h
diff --git a/third_party/WebKit/Source/modules/webaudio/AbstractAudioContext.h b/third_party/WebKit/Source/modules/webaudio/AbstractAudioContext.h
index 10c587fc0621f0e3013ba084c314bd4288190cb7..dde6ca92682b6bfaa02167743d6ff1782c504efa 100644
--- a/third_party/WebKit/Source/modules/webaudio/AbstractAudioContext.h
+++ b/third_party/WebKit/Source/modules/webaudio/AbstractAudioContext.h
@@ -35,6 +35,7 @@
 #include "modules/webaudio/AsyncAudioDecoder.h"
 #include "modules/webaudio/AudioDestinationNode.h"
 #include "modules/webaudio/DeferredTaskHandler.h"
+#include "modules/webaudio/IIRFilterNode.h"
 #include "platform/audio/AudioBus.h"
 #include "platform/heap/Handle.h"
 #include "wtf/HashSet.h"
@@ -62,6 +63,7 @@ class DynamicsCompressorNode;
 class ExceptionState;
 class GainNode;
 class HTMLMediaElement;
+class IIRFilterNode;
 class MediaElementAudioSourceNode;
 class MediaStreamAudioDestinationNode;
 class MediaStreamAudioSourceNode;
@@ -171,6 +173,10 @@ public:
     virtual ScriptPromise suspendContext(ScriptState*) = 0;
     virtual ScriptPromise resumeContext(ScriptState*) = 0;
 
+    // IIRFilter
+    IIRFilterNode* createIIRFilter(Vector<float> feedforwardCoef, Vector<float> feedbackCoef,
+        ExceptionState&);
+
     // When a source node has started processing and needs to be protected,
     // this method tells the context to protect the node.
     //