Add safety when the .src attribute of an <audio> or <video> element is changed and it's used with t…

Source/WebKit/chromium/src/WebMediaPlayerClientImpl.cpp

 // Copyright (c) 2009 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 "config.h"
 #include "WebMediaPlayerClientImpl.h"
 
 #include "InbandTextTrackPrivateImpl.h"
 #include "WebAudioSourceProvider.h"
 #include "WebDocument.h"
@@ skipping 823 matching lines @@
     , m_preload(MediaPlayer::MetaData)
     , m_videoLayer(0)
     , m_opaque(false)
     , m_needsWebLayerForVideo(false)
 {
 }
 
 #if ENABLE(WEB_AUDIO)
 void WebMediaPlayerClientImpl::AudioSourceProviderImpl::wrap(WebAudioSourceProvider* provider)
 {
+    MutexLocker locker(provideInputLock);
+
+    if (m_webAudioSourceProvider && provider != m_webAudioSourceProvider)
+        m_webAudioSourceProvider->setClient(0);
+
     m_webAudioSourceProvider = provider;
     if (m_webAudioSourceProvider)
         m_webAudioSourceProvider->setClient(m_client.get());
 }
 
 void WebMediaPlayerClientImpl::AudioSourceProviderImpl::setClient(AudioSourceProviderClient* client)
 {
+    MutexLocker locker(provideInputLock);
+
     if (client)
         m_client = adoptPtr(new WebMediaPlayerClientImpl::AudioClientImpl(client));
     else
         m_client.clear();
 
     if (m_webAudioSourceProvider)
         m_webAudioSourceProvider->setClient(m_client.get());
 }
 
 void WebMediaPlayerClientImpl::AudioSourceProviderImpl::provideInput(AudioBus* bus, size_t framesToProcess)
 {
     ASSERT(bus);
     if (!bus)
         return;
 
-    if (!m_webAudioSourceProvider) {
+    MutexTryLocker tryLocker(provideInputLock);
+    if (!tryLocker.locked() || !m_webAudioSourceProvider || !m_client.get()) {
         bus->zero();
         return;
     }
 
     // Wrap the AudioBus channel data using WebVector.
     size_t n = bus->numberOfChannels();
     WebVector<float*> webAudioData(n);
     for (size_t i = 0; i < n; ++i)
         webAudioData[i] = bus->channel(i)->mutableData();
 
     m_webAudioSourceProvider->provideInput(webAudioData, framesToProcess);
 }
 
 void WebMediaPlayerClientImpl::AudioClientImpl::setFormat(size_t numberOfChannels, float sampleRate)
 {
     if (m_client)
         m_client->setFormat(numberOfChannels, sampleRate);
 }
 
 #endif
 
 } // namespace WebKit