b=914030 remove MediaBufferDecoder::Shutdown(), no longer necessary since bug 900711, as part of making AudioContext::Shutdown() idempotent r=ehsan

--HG--
extra : transplant_source : %A8%BB%7D%A3%A6%87NF%F3%9D.Lu%D4%15B%10%9C%DFR

content/media/webaudio/AudioContext.cpp

@@ -517,26 +517,11 @@ GetHashtableElements(nsTHashtable<nsPtrHashKey<T> >& aHashtable, nsTArray<T*>& a
   aHashtable.EnumerateEntries(&GetHashtableEntry<T>, &aArray);
 }
 
-void
-AudioContext::ShutdownDecoder()
-{
-  mDecoder.Shutdown();
-}
-
 void
 AudioContext::Shutdown()
 {
   Suspend();
 
-  // We need to hold the AudioContext object alive here to make sure that
-  // it doesn't get destroyed before our decoder shutdown runnable has had
-  // a chance to run.
-  nsCOMPtr<nsIRunnable> threadShutdownEvent =
-    NS_NewRunnableMethod(this, &AudioContext::ShutdownDecoder);
-  if (threadShutdownEvent) {
-    NS_DispatchToCurrentThread(threadShutdownEvent);
-  }
-
   // Stop all audio buffer source nodes, to make sure that they release
   // their self-references.
   // We first gather an array of the nodes and then call Stop on each one,

content/media/webaudio/MediaBufferDecoder.cpp

@@ -572,15 +572,6 @@ MediaBufferDecoder::EnsureThreadPoolInitialized()
   return true;
 }
 
-void
-MediaBufferDecoder::Shutdown() {
-  if (mThreadPool) {
-    mThreadPool->Shutdown();
-    mThreadPool = nullptr;
-  }
-  MOZ_ASSERT(!mThreadPool);
-}
-
 WebAudioDecodeJob::WebAudioDecodeJob(const nsACString& aContentType,
                                      AudioContext* aContext,
                                      const ArrayBuffer& aBuffer,

content/media/webaudio/MediaBufferDecoder.h

@@ -80,8 +80,6 @@ public:
   bool SyncDecodeMedia(const char* aContentType, uint8_t* aBuffer,
                        uint32_t aLength, WebAudioDecodeJob& aDecodeJob);
 
-  void Shutdown();
-
 private:
   bool EnsureThreadPoolInitialized();