Move the exception logic to the AudioNode creator

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

Index: third_party/WebKit/Source/modules/webaudio/MediaStreamAudioSourceNode.cpp
diff --git a/third_party/WebKit/Source/modules/webaudio/MediaStreamAudioSourceNode.cpp b/third_party/WebKit/Source/modules/webaudio/MediaStreamAudioSourceNode.cpp
index 860dd15b712c2289b834bdc08f51a65cc7068928..536db5f82f9bbf0f83f8f4514f4a19fd86ddad34 100644
--- a/third_party/WebKit/Source/modules/webaudio/MediaStreamAudioSourceNode.cpp
+++ b/third_party/WebKit/Source/modules/webaudio/MediaStreamAudioSourceNode.cpp
@@ -23,6 +23,8 @@
  */
 
 #include "modules/webaudio/MediaStreamAudioSourceNode.h"
+
+#include "core/dom/ExceptionCode.h"
 #include "modules/webaudio/AbstractAudioContext.h"
 #include "modules/webaudio/AudioNodeOutput.h"
 #include "platform/Logging.h"
@@ -114,9 +116,37 @@ MediaStreamAudioSourceNode::MediaStreamAudioSourceNode(AbstractAudioContext& con
     setHandler(MediaStreamAudioSourceHandler::create(*this, mediaStream, audioTrack, std::move(audioSourceProvider)));
 }
 
-MediaStreamAudioSourceNode* MediaStreamAudioSourceNode::create(AbstractAudioContext& context, MediaStream& mediaStream, MediaStreamTrack* audioTrack, PassOwnPtr<AudioSourceProvider> audioSourceProvider)
+MediaStreamAudioSourceNode* MediaStreamAudioSourceNode::create(AbstractAudioContext& context, MediaStream& mediaStream, ExceptionState& exceptionState)
 {
-    return new MediaStreamAudioSourceNode(context, mediaStream, audioTrack, std::move(audioSourceProvider));
+    ASSERT(isMainThread());

[hongchan, 2016/05/13 01:20:12]

DCHECK.

[Raymond Toy, 2016/05/20 23:12:00]

Done.

+
+    if (context.isContextClosed()) {
+        context.throwExceptionForClosedState(exceptionState);
+        return nullptr;
+    }
+
+    MediaStreamTrackVector audioTracks = mediaStream.getAudioTracks();
+    if (audioTracks.isEmpty()) {
+        exceptionState.throwDOMException(
+            InvalidStateError,
+            "MediaStream has no audio track");
+        return nullptr;
+    }
+
+    // Use the first audio track in the media stream.
+    MediaStreamTrack* audioTrack = audioTracks[0];
+    OwnPtr<AudioSourceProvider> provider = audioTrack->createWebAudioSource();
+
+    MediaStreamAudioSourceNode* node = new MediaStreamAudioSourceNode(context, mediaStream, audioTrack, provider.release());

[hongchan, 2016/05/13 01:20:12]

Over 80 cols. Let's wrap these arguments.

+
+    if (node) {
+        // FIXME: Only stereo streams are supported right now. We should be able to accept multi-channel streams.

[hongchan, 2016/05/13 01:20:12]

Over 80 cols. Let's change it to 'TODO'. You can put my ID here.

[Raymond Toy, 2016/05/20 23:12:00]

Done.

+        node->setFormat(2, context.sampleRate());
+        // context keeps reference until node is disconnected
+        context.notifySourceNodeStartedProcessing(node);
+    }
+
+    return node;

[hongchan, 2016/05/13 01:20:12]

We should return nullptr when |node| is invalid and do the rest otherwise.

 }
 
 DEFINE_TRACE(MediaStreamAudioSourceNode)