Move the exception logic to the AudioNode creator

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

 /*
  * Copyright (C) 2011, Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1.  Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 188 matching lines @@
 }
 
 // ----------------------------------------------------------------
 
 MediaElementAudioSourceNode::MediaElementAudioSourceNode(AbstractAudioContext& context, HTMLMediaElement& mediaElement)
     : AudioSourceNode(context)
 {
     setHandler(MediaElementAudioSourceHandler::create(*this, mediaElement));
 }
 
-MediaElementAudioSourceNode* MediaElementAudioSourceNode::create(AbstractAudioContext& context, HTMLMediaElement& mediaElement)
+MediaElementAudioSourceNode* MediaElementAudioSourceNode::create(AbstractAudioContext& context, HTMLMediaElement& mediaElement, ExceptionState& exceptionState)
 {
-    return new MediaElementAudioSourceNode(context, mediaElement);
+    DCHECK(isMainThread());
+
+    if (context.isContextClosed()) {
+        context.throwExceptionForClosedState(exceptionState);
+        return nullptr;
+    }
+
+    // First check if this media element already has a source node.
+    if (mediaElement.audioSourceNode()) {
+        exceptionState.throwDOMException(
+            InvalidStateError,
+            "HTMLMediaElement already connected previously to a different MediaElementSourceNode.");
+        return nullptr;
+    }
+
+    MediaElementAudioSourceNode* node = new MediaElementAudioSourceNode(context, mediaElement);
+
+    if (node) {
+        mediaElement.setAudioSourceNode(node);
+        // context keeps reference until node is disconnected
+        context.notifySourceNodeStartedProcessing(node);
+    }
+
+    return node;
 }
 
 DEFINE_TRACE(MediaElementAudioSourceNode)
 {
     AudioSourceProviderClient::trace(visitor);
     AudioSourceNode::trace(visitor);
 }
 
 MediaElementAudioSourceHandler& MediaElementAudioSourceNode::mediaElementAudioSourceHandler() const
 {
@@ skipping 20 matching lines @@
     mediaElementAudioSourceHandler().lock();
 }
 
 void MediaElementAudioSourceNode::unlock()
 {
     mediaElementAudioSourceHandler().unlock();
 }
 
 } // namespace blink