Add dictionary for OfflineAudioContext constructor

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

Index: third_party/WebKit/Source/modules/webaudio/OfflineAudioContext.cpp
diff --git a/third_party/WebKit/Source/modules/webaudio/OfflineAudioContext.cpp b/third_party/WebKit/Source/modules/webaudio/OfflineAudioContext.cpp
index b110337e3cff61227fb946f8ff824c10f16a177c..8a99df81245e5676ce500766137dd496d890725f 100644
--- a/third_party/WebKit/Source/modules/webaudio/OfflineAudioContext.cpp
+++ b/third_party/WebKit/Source/modules/webaudio/OfflineAudioContext.cpp
@@ -34,6 +34,7 @@
 #include "modules/webaudio/AudioListener.h"
 #include "modules/webaudio/DeferredTaskHandler.h"
 #include "modules/webaudio/OfflineAudioCompletionEvent.h"
+#include "modules/webaudio/OfflineAudioContextOptions.h"
 #include "modules/webaudio/OfflineAudioDestinationNode.h"
 
 #include "platform/CrossThreadFunctional.h"
@@ -128,6 +129,26 @@ OfflineAudioContext* OfflineAudioContext::Create(
   return audio_context;
 }
 
+OfflineAudioContext* OfflineAudioContext::Create(
+    ExecutionContext* context,
+    const OfflineAudioContextOptions& options,
+    ExceptionState& exception_state) {
+  OfflineAudioContext* offline_context =
+      Create(context, options.hasChannelCount() ? options.channelCount() : 1,
+             options.length(), options.sampleRate(), exception_state);
+  if (offline_context) {
+    offline_context->DestinationHandler().SetChannelCountMode(
+        options.hasChannelCountMode() ? options.channelCountMode() : "explicit",
+        exception_state);
+    offline_context->DestinationHandler().SetChannelInterpretation(
+        options.hasChannelInterpretation() ? options.channelInterpretation()
+                                           : "speakers",
+        exception_state);
+  }
+
+  return offline_context;
+}
+
 OfflineAudioContext::OfflineAudioContext(Document* document,
                                          unsigned number_of_channels,
                                          size_t number_of_frames,