Add WebThread in AudioDestination to support AudioWorkletThread

third_party/WebKit/Source/platform/audio/PushPullFIFO.cpp

Index: third_party/WebKit/Source/platform/audio/PushPullFIFO.cpp
diff --git a/third_party/WebKit/Source/platform/audio/PushPullFIFO.cpp b/third_party/WebKit/Source/platform/audio/PushPullFIFO.cpp
index 73b1ef44bf04591cdc283b1de4bf808e7b6e8ee8..575b2c7e2e41886d126d1e52c846433873d7455b 100644
--- a/third_party/WebKit/Source/platform/audio/PushPullFIFO.cpp
+++ b/third_party/WebKit/Source/platform/audio/PushPullFIFO.cpp
@@ -34,6 +34,8 @@ PushPullFIFO::~PushPullFIFO() {}
 // Push the data from |inputBus| to FIFO. The size of push is determined by
 // the length of |inputBus|.
 void PushPullFIFO::push(const AudioBus* inputBus) {
+  MutexLocker locker(m_lock);
+
   CHECK(inputBus);
   CHECK_EQ(inputBus->length(), AudioUtilities::kRenderQuantumFrames);
   SECURITY_CHECK(inputBus->length() <= m_fifoLength);
@@ -83,6 +85,8 @@ void PushPullFIFO::push(const AudioBus* inputBus) {
 // Pull the data out of FIFO to |outputBus|. If remaining frame in the FIFO
 // is less than the frames to pull, provides remaining frame plus the silence.
 void PushPullFIFO::pull(AudioBus* outputBus, size_t framesRequested) {
+  MutexLocker locker(m_lock);
+
 #if OS(ANDROID)
   if (!outputBus) {
     // Log when outputBus or FIFO object is invalid. (crbug.com/692423)