Use background thread for AsyncAudioDecoder

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

Index: third_party/WebKit/Source/modules/webaudio/AsyncAudioDecoder.cpp
diff --git a/third_party/WebKit/Source/modules/webaudio/AsyncAudioDecoder.cpp b/third_party/WebKit/Source/modules/webaudio/AsyncAudioDecoder.cpp
index 2c30b37c4134e5e64cb9cf795c1976b6b382f3a5..b7432b41a15ede884aeeb0016552f8a2db4d0e69 100644
--- a/third_party/WebKit/Source/modules/webaudio/AsyncAudioDecoder.cpp
+++ b/third_party/WebKit/Source/modules/webaudio/AsyncAudioDecoder.cpp
@@ -30,21 +30,13 @@
 #include "platform/CrossThreadFunctional.h"
 #include "platform/audio/AudioBus.h"
 #include "platform/audio/AudioFileReader.h"
+#include "platform/threading/BackgroundTaskRunner.h"
 #include "public/platform/Platform.h"
 #include "public/platform/WebTraceLocation.h"
 #include "wtf/PtrUtil.h"
 
 namespace blink {
 
-AsyncAudioDecoder::AsyncAudioDecoder()
-    : m_thread(wrapUnique(Platform::current()->createThread("Audio Decoder")))
-{
-}
-
-AsyncAudioDecoder::~AsyncAudioDecoder()
-{
-}
-
 void AsyncAudioDecoder::decodeAsync(DOMArrayBuffer* audioData, float sampleRate, AudioBufferCallback* successCallback, AudioBufferCallback* errorCallback, ScriptPromiseResolver* resolver, BaseAudioContext* context)
 {
     DCHECK(isMainThread());
@@ -52,11 +44,13 @@ void AsyncAudioDecoder::decodeAsync(DOMArrayBuffer* audioData, float sampleRate,
     if (!audioData)
         return;
 
-    m_thread->getWebTaskRunner()->postTask(BLINK_FROM_HERE, crossThreadBind(&AsyncAudioDecoder::decode, wrapCrossThreadPersistent(audioData), sampleRate, wrapCrossThreadPersistent(successCallback), wrapCrossThreadPersistent(errorCallback), wrapCrossThreadPersistent(resolver), wrapCrossThreadPersistent(context)));
+    BackgroundTaskRunner::TaskSize taskSize = BackgroundTaskRunner::TaskSizeShortRunningTask;

[Raymond Toy, 2016/08/24 23:08:46]

Why short?  Decoding long files is probably not a short running task.

[hongchan, 2016/08/24 23:10:19]

TODO: The threshold for long/short task needs to be defined.

+    BackgroundTaskRunner::postOnBackgroundThread(BLINK_FROM_HERE, crossThreadBind(&AsyncAudioDecoder::decodeOnBackgroundThread, wrapCrossThreadPersistent(audioData), sampleRate, wrapCrossThreadPersistent(successCallback), wrapCrossThreadPersistent(errorCallback), wrapCrossThreadPersistent(resolver), wrapCrossThreadPersistent(context)), taskSize);
 }
 
-void AsyncAudioDecoder::decode(DOMArrayBuffer* audioData, float sampleRate, AudioBufferCallback* successCallback, AudioBufferCallback* errorCallback, ScriptPromiseResolver* resolver, BaseAudioContext* context)
+void AsyncAudioDecoder::decodeOnBackgroundThread(DOMArrayBuffer* audioData, float sampleRate, AudioBufferCallback* successCallback, AudioBufferCallback* errorCallback, ScriptPromiseResolver* resolver, BaseAudioContext* context)
 {
+    DCHECK(!isMainThread());
     RefPtr<AudioBus> bus = createBusFromInMemoryAudioFile(audioData->data(), audioData->byteLength(), false, sampleRate);
 
     // Decoding is finished, but we need to do the callbacks on the main thread.