Add constructors for WebAudio events

third_party/WebKit/Source/modules/webaudio/AudioProcessingEventInit.idl

Index: third_party/WebKit/Source/modules/webaudio/AudioProcessingEventInit.idl
diff --git a/third_party/WebKit/Source/modules/webaudio/AudioProcessingEventInit.idl b/third_party/WebKit/Source/modules/webaudio/AudioProcessingEventInit.idl
new file mode 100644
index 0000000000000000000000000000000000000000..eda9d939cfbd2fd7166b4c7b6cdd275a5d351cd1
--- /dev/null
+++ b/third_party/WebKit/Source/modules/webaudio/AudioProcessingEventInit.idl
@@ -0,0 +1,10 @@
+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// See https://webaudio.github.io/web-audio-api/#audioprocessingeventinit
+dictionary AudioProcessingEventInit : EventInit {
+    required double playbackTime;
+    required AudioBuffer inputBuffer;
+    required AudioBuffer outputBuffer;
+};