MediaRecorder: fire onError if the amount of tracks of the MediaStream varies

third_party/WebKit/Source/modules/mediarecorder/MediaRecorder.cpp

 // Copyright 2015 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.
 
 #include "modules/mediarecorder/MediaRecorder.h"
 
 #include "bindings/core/v8/Dictionary.h"
 #include "core/events/Event.h"
 #include "core/fileapi/Blob.h"
 #include "modules/EventTargetModules.h"
@@ skipping 37 matching lines @@
 {
     MediaRecorder* recorder = new MediaRecorder(context, stream, options, exceptionState);
     recorder->suspendIfNeeded();
 
     return recorder;
 }
 
 MediaRecorder::MediaRecorder(ExecutionContext* context, MediaStream* stream, const MediaRecorderOptions& options, ExceptionState& exceptionState)
     : ActiveDOMObject(context)
     , m_stream(stream)
+    , m_streamAmountOfTracks(stream->getTracks().size())
     , m_mimeType(options.mimeType())
     , m_stopped(true)
     , m_ignoreMutedMedia(true)
     , m_state(State::Inactive)
     , m_dispatchScheduledEventRunner(this, &MediaRecorder::dispatchScheduledEvent)
 {
     ASSERT(m_stream->getTracks().size());
 
     m_recorderHandler = adoptPtr(Platform::current()->createMediaRecorderHandler());
     ASSERT(m_recorderHandler);
@@ skipping 130 matching lines @@
     m_stream.clear();
     m_recorderHandler.clear();
 }
 
 void MediaRecorder::writeData(const char* data, size_t length, bool lastInSlice)
 {
     if (m_stopped && !lastInSlice) {
         m_stopped = false;
         scheduleDispatchEvent(Event::create(EventTypeNames::start));
     }
+    if (m_stream && m_streamAmountOfTracks != m_stream->getTracks().size()) {
+        m_streamAmountOfTracks = m_stream->getTracks().size();
+        onError("Amount of tracks in MediaStream has changed.");
+    }
 
     // TODO(mcasas): Act as |m_ignoredMutedMedia| instructs if |m_stream| track(s) is in muted() state.
 
     if (!m_blobData)
         m_blobData = BlobData::create();
     if (data)
         m_blobData->appendBytes(data, length);
 
     if (!lastInSlice)
         return;
 
     // Cache |m_blobData->length()| before release()ng it.
     const long long blobDataLength = m_blobData->length();
     createBlobEvent(Blob::create(BlobDataHandle::create(m_blobData.release(), blobDataLength)));
 }
 
 void MediaRecorder::onError(const WebString& message)
 {
     // TODO(mcasas): Beef up the Error Event and add the |message|, see https://github.com/w3c/mediacapture-record/issues/31
     scheduleDispatchEvent(Event::create(EventTypeNames::error));
-
-    if (m_state == State::Recording)
-        stopRecording();
 }
 
 void MediaRecorder::createBlobEvent(Blob* blob)
 {
     // TODO(mcasas): Consider launching an Event with a TypedArray inside, see https://github.com/w3c/mediacapture-record/issues/17.
     scheduleDispatchEvent(BlobEvent::create(EventTypeNames::dataavailable, blob));
 }
 
 void MediaRecorder::stopRecording()
 {
@@ skipping 24 matching lines @@
 
 DEFINE_TRACE(MediaRecorder)
 {
     visitor->trace(m_stream);
     visitor->trace(m_scheduledEvents);
     RefCountedGarbageCollectedEventTargetWithInlineData<MediaRecorder>::trace(visitor);
     ActiveDOMObject::trace(visitor);
 }
 
 } // namespace blink